Consolidate duplicate train-travel.yaml files

[coderabbitai]

Context

This issue tracks the consolidation of duplicate OpenAPI specification files identified in PR #26.

Current state:

• packages/examples/resources/train-travel.yaml
• packages/zenko/src/resources/train-travel.yaml

These files are currently identical copies, which increases maintenance burden and risk of divergence.

Related PR: #26
Discussion: #26 (comment)

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Proposed Solutions

Consider one of these approaches:

1. Use symbolic links

Move the canonical spec to one location and create symlinks from the other package(s):

cd packages/examples/resources
ln -s ../../zenko/src/resources/train-travel.yaml train-travel.yaml

2. Shared location at repo root

Move the spec to a shared location (e.g., specs/train-travel.yaml at the monorepo root) and reference it from both packages.

3. Document intentional duplication

If duplication is intentional (e.g., examples should be self-contained), add a comment at the top of both files indicating they should be kept in sync, and consider adding a test to verify they match.

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Acceptance Criteria

• Canonical location established for train-travel.yaml
• Duplicate eliminated or documented with sync mechanism
• CI check added to prevent future drift (if using symlinks or requiring sync)
• Documentation updated if necessary

Target: Future resources package PR