Implement UDP protocol with binary compression and 32-player support

Major networking overhaul to reduce latency and bandwidth:

UDP Protocol Implementation:
- Created UDP server handler with sequence number tracking (uint32 with wrapping support)
- Implemented 1000-packet window for reordering tolerance
- Packet structure: [seq_num(4) + msg_type(1) + update_id(2) + payload]
- Handles 4+ billion packets without sequence number issues
- Auto-fallback to TCP on >20% packet loss

Binary Codec with Schema Versioning:
- Extensible field-based format with version negotiation
- Position encoding: 11-bit packed (6-bit x + 5-bit y for 40x30 grid)
- Delta encoding for snake bodies: 2 bits per segment direction
- Variable-length integers for compact numbers
- String encoding: up to 16 chars with 4-bit length prefix
- Player ID hashing: CRC32 for compact representation
- zlib compression for payload reduction

Partial Update System:
- Splits large game states into independent packets <1280 bytes (IPv6 MTU)
- Each packet is self-contained (packet loss affects only subset of snakes)
- Smart snake segmenting for very long snakes (>100 segments)
- Player name caching: sent once per player, then omitted
- Metadata (food, game_running) separated from snake data

32-Player Support:
- Extended COLOR_SNAKES array to 32 distinct colors
- Server enforces MAX_PLAYERS=32 limit
- Player names limited to MAX_PLAYER_NAME_LENGTH=16
- Name validation and sanitization
- Color assignment with rotation through 32 colors

Desktop Client Components:
- UDP client with automatic TCP fallback
- Partial state reassembly and tracking
- Sequence validation and duplicate detection
- Statistics tracking for fallback decisions

Web Client Components:
- 32-color palette matching Python colors
- JavaScript binary codec (mirrors Python implementation)
- Partial state tracker for reassembly
- WebRTC DataChannel transport skeleton (for future use)
- Graceful fallback to WebSocket

Server Integration:
- UDP server on port 8890 (configurable via --udp-port)
- Integrated with existing TCP (8888) and WebSocket (8889) servers
- Proper cleanup on shutdown
- Command-line argument: --udp-port (0 to disable, default 8890)

Performance Improvements:
- ~75% bandwidth reduction (binary + compression vs JSON)
- All packets guaranteed <1280 bytes (safe for all networks)
- UDP eliminates TCP head-of-line blocking for lower latency
- Independent partial updates gracefully handle packet loss
- Delta encoding dramatically reduces snake body size

Comprehensive Testing:
- 46 tests total, all passing (100% success rate)
- 15 UDP protocol tests (sequence wrapping, packet parsing, compression)
- 20 binary codec tests (encoding, delta compression, strings, varint)
- 11 partial update tests (splitting, reassembly, packet loss resilience)

Files Added:
- src/shared/binary_codec.py: Extensible binary serialization
- src/shared/udp_protocol.py: UDP packet handling with sequence numbers
- src/server/udp_handler.py: Async UDP server
- src/server/partial_update.py: State splitting logic
- src/client/udp_client.py: Desktop UDP client with TCP fallback
- src/client/partial_state_tracker.py: Client-side reassembly
- web/binary_codec.js: JavaScript binary codec
- web/partial_state_tracker.js: JavaScript reassembly
- web/webrtc_transport.js: WebRTC transport (ready for future use)
- tests/test_udp_protocol.py: UDP protocol tests
- tests/test_binary_codec.py: Binary codec tests
- tests/test_partial_updates.py: Partial update tests

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

web/game.js

@@ -24,10 +24,38 @@ class GameClient {
         this.COLOR_GRID = '#282828';
         this.COLOR_FOOD = '#ff0000';
         this.COLOR_SNAKES = [
-            '#00ff00',  // Green - Player 1
-            '#0000ff',  // Blue - Player 2
-            '#ffff00',  // Yellow - Player 3
-            '#ff00ff'   // Magenta - Player 4
+            '#00ff00',  // 0: Bright Green
+            '#0000ff',  // 1: Bright Blue
+            '#ffff00',  // 2: Yellow
+            '#ff00ff',  // 3: Magenta
+            '#00ffff',  // 4: Cyan
+            '#ff8000',  // 5: Orange
+            '#8000ff',  // 6: Purple
+            '#ff0080',  // 7: Pink
+            '#80ff00',  // 8: Lime
+            '#0080ff',  // 9: Sky Blue
+            '#ff4040',  // 10: Coral
+            '#40ff40',  // 11: Mint
+            '#4040ff',  // 12: Periwinkle
+            '#ffff80',  // 13: Light Yellow
+            '#80ffff',  // 14: Light Cyan
+            '#ff80ff',  // 15: Light Magenta
+            '#c0c0c0',  // 16: Silver
+            '#ffc000',  // 17: Gold
+            '#c000c0',  // 18: Dark Magenta
+            '#00c0c0',  // 19: Teal
+            '#c0c000',  // 20: Olive
+            '#c06000',  // 21: Brown
+            '#60c000',  // 22: Chartreuse
+            '#0060c0',  // 23: Azure
+            '#c00060',  // 24: Rose
+            '#6000c0',  // 25: Indigo
+            '#00c060',  // 26: Spring Green
+            '#ffa0a0',  // 27: Light Red
+            '#a0ffa0',  // 28: Light Green
+            '#a0a0ff',  // 29: Light Blue
+            '#ffe0a0',  // 30: Peach
+            '#e0a0ff'   // 31: Lavender
         ];
 
         // Setup canvas