Add CAKE traffic shaping support for bandwidth management

[amirhmoradi]

This commit implements CAKE (Common Applications Kept Enhanced) traffic shaping for Wiregate, addressing upstream issue #77.

CAKE is a modern Linux kernel qdisc that provides superior bufferbloat control, fair queuing, and automatic bandwidth management compared to traditional traffic shapers.

Key Features:

• Reduced latency under load (< 20ms vs 500ms+ without shaping)
• Fair bandwidth distribution across VPN clients
• NAT-aware per-host and per-flow fair queuing
• Built-in ACK filtering for asymmetric connections
• Automatic rate adaptation
• Minimal configuration required

Implementation Details:

1. Docker Infrastructure (WG-Dash/Dockerfile):

   • Added iproute2 package for tc command support

2. Python Layer (WG-Dash/src/traffic_control.py):

   • New TrafficControl module with CAKEQdisc class
   • Functions for applying/removing CAKE qdisc
   • Validation and error handling
   • Statistics collection
   • Support for all CAKE parameters (bandwidth, overhead, mpu, options)

3. Shell Scripts (WG-Dash/src/iptable-rules/*/):

   • cake-setup.sh: Apply CAKE to WireGuard interface (all zones)
   • cake-teardown.sh: Remove CAKE from interface (all zones)
   • Integrated with existing postup.sh and postdown.sh scripts
   • Environment variable-based configuration
   • Graceful fallback if CAKE unavailable

4. Per-Zone Configuration:

   • ADMINS: 1 Gbit/s (full-speed admin access)
   • MEMBERS: 100 Mbit/s (standard users)
   • GUESTS: 50 Mbit/s (limited guest access)
   • LANP2P: 100 Mbit/s (LAN-only connections)

5. Configuration (via environment variables):

   • CAKE_ENABLED: Global enable/disable toggle (default: false)
   • CAKE_BANDWIDTH_*: Per-zone bandwidth limits
   • CAKE_OVERHEAD: Overhead compensation for encapsulation
   • CAKE_MPU: Minimum packet unit
   • CAKE_MEMLIMIT: Memory limit for queues
   • CAKE_OPTIONS: Space-separated CAKE options

6. Documentation:

   • docs/CAKE_TRAFFIC_SHAPING.md: Comprehensive guide
   • examples/cake-config.env.example: Example configurations
   • README.md: Quick start guide and feature overview
   • Docs/CHANGELOG.md: Version history entry

Design Principles:

• Optional feature, disabled by default
• Zero impact on existing functionality when disabled
• Clean integration with existing network scripts
• Environment variable driven configuration
• Comprehensive documentation and examples

Testing Recommendations:

1. Verify CAKE availability: tc qdisc add dev lo root cake help
2. Check interface setup: tc qdisc show dev MEMBERS
3. Monitor statistics: tc -s qdisc show dev MEMBERS
4. Test latency under load: ping + large download

Addresses: #77

[amirhmoradi]

closing in favor of the new PR ( #99 ) which is correctly based on bug-hunting branch.