chore(repo): Add templates for issues, pull requests, and contributing.

.github/ISSUE_TEMPLATE/bug.yml

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+name: Bug Report
+description: Report incorrect behavior or a defect in lambda-rs.
+title: "[Bug] "
+labels: ["bug"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Use this template to report bugs. Provide sufficient detail for
+        maintainers to reproduce and diagnose the issue.
+
+  - type: textarea
+    id: summary
+    attributes:
+      label: Summary
+      description: A concise description of the bug.
+      placeholder: Describe the incorrect behavior in one or two sentences.
+    validations:
+      required: true
+
+  - type: textarea
+    id: expected-behavior
+    attributes:
+      label: Expected Behavior
+      description: Describe what should happen.
+      placeholder: The expected correct behavior.
+    validations:
+      required: true
+
+  - type: textarea
+    id: actual-behavior
+    attributes:
+      label: Actual Behavior
+      description: Describe what currently happens.
+      placeholder: The observed incorrect behavior.
+    validations:
+      required: true
+
+  - type: textarea
+    id: reproduction-steps
+    attributes:
+      label: Reproduction Steps
+      description: Provide minimal steps to reproduce the issue.
+      placeholder: |
+        1. Clone repository
+        2. Run `cargo run --example <name>`
+        3. Observe error/unexpected behavior
+    validations:
+      required: true
+
+  - type: textarea
+    id: code-sample
+    attributes:
+      label: Code Sample
+      description: Include a minimal code snippet that demonstrates the issue.
+      placeholder: |
+        ```rust
+        // Minimal reproduction code
+        fn main() {
+          // ...
+        }
+        ```
+      render: rust
+    validations:
+      required: false
+
+  - type: textarea
+    id: environment
+    attributes:
+      label: Environment
+      description: Provide details about the environment.
+      placeholder: |
+        - OS: macOS 14.0 / Windows 11 / Ubuntu 24.04
+        - Rust version: `rustc --version`
+        - GPU: NVIDIA RTX 4090 / Apple M3 / Intel UHD 770
+        - Graphics backend: Vulkan / Metal / DX12
+        - lambda-rs version or commit: `main` / `abc1234`
+    validations:
+      required: true
+
+  - type: dropdown
+    id: affected-crates
+    attributes:
+      label: Affected Crates
+      description: Select the crate(s) this bug impacts.
+      multiple: true
+      options:
+        - lambda-rs
+        - lambda-rs-platform
+        - lambda-rs-args
+        - lambda-rs-logging
+        - Unknown
+    validations:
+      required: true
+
+  - type: textarea
+    id: logs-output
+    attributes:
+      label: Logs and Output
+      description: Include relevant error messages, stack traces, or console output.
+      placeholder: |
+        ```
+        error[E0XXX]: ...
+        ```
+      render: shell
+    validations:
+      required: false
+
+  - type: textarea
+    id: additional-context
+    attributes:
+      label: Additional Context
+      description: Any other information that may help diagnose the issue.
+      placeholder: |
+        - Related issues
+        - Screenshots or screen recordings (for visual bugs)
+        - Workarounds discovered
+    validations:
+      required: false

.github/ISSUE_TEMPLATE/config.yml

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+blank_issues_enabled: false
+contact_links:
+  - name: Discussions
+    url: https://github.com/lambda-sh/lambda/discussions
+    about: Use discussions for general questions, ideas, or community support.

.github/ISSUE_TEMPLATE/documentation.yml

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+name: Documentation
+description: Report missing, incorrect, or unclear documentation.
+title: "[Docs] "
+labels: ["documentation"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Use this template to report documentation issues or request improvements.
+
+  - type: textarea
+    id: summary
+    attributes:
+      label: Summary
+      description: Describe the documentation issue or improvement.
+      placeholder: A concise description of what is missing, incorrect, or unclear.
+    validations:
+      required: true
+
+  - type: dropdown
+    id: documentation-type
+    attributes:
+      label: Documentation Type
+      description: Select the type of documentation affected.
+      options:
+        - API documentation (rustdoc)
+        - Specification (docs/specs/)
+        - Tutorial (docs/tutorials/)
+        - Guide (docs/)
+        - README
+        - Code comments
+        - Other
+    validations:
+      required: true
+
+  - type: textarea
+    id: location
+    attributes:
+      label: Location
+      description: Identify the file path or URL of the affected documentation.
+      placeholder: |
+        - File: `docs/tutorials/uniform-buffers.md`
+        - Module: `lambda_rs::render`
+        - URL: https://docs.rs/lambda-rs/...
+    validations:
+      required: false
+
+  - type: textarea
+    id: current-content
+    attributes:
+      label: Current Content
+      description: Quote or describe the current documentation (if applicable).
+      placeholder: |
+        The current documentation states:
+        > "..."
+    validations:
+      required: false
+
+  - type: textarea
+    id: proposed-change
+    attributes:
+      label: Proposed Change
+      description: Describe the improvement or correction.
+      placeholder: |
+        The documentation should:
+        - Clarify X
+        - Add example for Y
+        - Correct statement about Z
+    validations:
+      required: true
+
+  - type: textarea
+    id: additional-context
+    attributes:
+      label: Additional Context
+      description: Any other relevant information.
+      placeholder: |
+        - Related code changes
+        - User confusion observed
+    validations:
+      required: false

.github/ISSUE_TEMPLATE/feature.yml

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+name: Feature Request
+description: Propose a new feature or enhancement for lambda-rs.
+title: "[Feature] "
+labels: ["enhancement"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Use this template to propose new functionality or enhancements. Provide
+        sufficient detail for maintainers to evaluate scope, feasibility, and
+        alignment with project goals.
+
+  - type: textarea
+    id: overview
+    attributes:
+      label: Overview
+      description: A concise summary of the proposed feature and its purpose.
+      placeholder: |
+        Describe the feature in one paragraph. Include the problem it solves and
+        the expected outcome.
+    validations:
+      required: true
+
+  - type: textarea
+    id: current-state
+    attributes:
+      label: Current State
+      description: Describe the current behavior or limitation that motivates this request.
+      placeholder: |
+        Reference existing code, APIs, or behavior. Include file paths or code snippets where relevant.
+        Example:
+        ```rust
+        // crates/lambda-rs/src/example.rs:42-50
+        // Current implementation does X but lacks Y
+        ```
+    validations:
+      required: false
+
+  - type: textarea
+    id: scope
+    attributes:
+      label: Scope
+      description: Define goals and non-goals for this feature.
+      placeholder: |
+        **Goals:**
+        - Goal 1
+        - Goal 2
+
+        **Non-Goals:**
+        - Item explicitly out of scope
+    validations:
+      required: true
+
+  - type: textarea
+    id: proposed-api
+    attributes:
+      label: Proposed API
+      description: Outline the public API surface, types, and usage patterns.
+      placeholder: |
+        ```rust
+        pub struct ExampleBuilder {
+          // fields
+        }
+
+        impl ExampleBuilder {
+          pub fn new() -> Self;
+          pub fn with_option(self, value: u32) -> Self;
+          pub fn build(self) -> Result<Example, ExampleError>;
+        }
+        ```
+
+        **Example Usage:**
+        ```rust
+        let example = ExampleBuilder::new()
+          .with_option(42)
+          .build()?;
+        ```
+    validations:
+      required: false
+
+  - type: textarea
+    id: acceptance-criteria
+    attributes:
+      label: Acceptance Criteria
+      description: List concrete, testable criteria for completion.
+      placeholder: |
+        - [ ] Criterion 1
+        - [ ] Criterion 2
+        - [ ] Documentation updated
+        - [ ] Example added or updated
+    validations:
+      required: true
+
+  - type: dropdown
+    id: affected-crates
+    attributes:
+      label: Affected Crates
+      description: Select the crate(s) this feature impacts.
+      multiple: true
+      options:
+        - lambda-rs
+        - lambda-rs-platform
+        - lambda-rs-args
+        - lambda-rs-logging
+        - Other/Multiple
+    validations:
+      required: true
+
+  - type: textarea
+    id: notes
+    attributes:
+      label: Notes
+      description: Additional context, constraints, or considerations.
+      placeholder: |
+        - Related issues or PRs
+        - Platform-specific considerations
+        - Future work explicitly deferred
+    validations:
+      required: false