v0.2.0 transitioned to api-only, extended and improved features, docs and tests added

doc/development.md

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+# Development Guide
+
+## Prerequisites
+
+- Go 1.24+
+- Stockfish in PATH
+- Git
+- curl, jq (for testing)
+
+## Building
+
+```bash
+git clone https://git.lixen.com/lixen/chess
+cd chess
+go build ./cmd/chessd
+```
+
+## Running
+
+### Flags
+- `-host`: Server host (default: localhost)
+- `-port`: Server port (default: 8080)
+- `-dev`: Development mode with relaxed rate limits
+
+### Modes
+```bash
+# Production (1 req/s rate limit)
+./chessd
+
+# Development (10 req/s rate limit)
+./chessd -dev
+```
+
+## Project Structure
+
+```
+chess/
+├── cmd/chessd/        # Entry point
+├── internal/
+│   ├── board/         # FEN/ASCII operations
+│   ├── core/          # Shared types
+│   ├── engine/        # Stockfish UCI wrapper
+│   ├── game/          # Game state
+│   ├── http/          # Fiber handlers
+│   ├── processor/     # Command processing
+│   └── service/       # State management
+└── test/              # Test scripts
+```
+
+## Testing
+
+```bash
+# Unit tests
+go test ./...
+
+# API tests (requires dev mode)
+./chessd -dev &
+./test/test-api.sh
+```
+
+Test script validates:
+- Basic CRUD operations
+- Computer move triggering ("cccc" mechanism)
+- Pending state protection
+- Rate limiting
+- Input validation
+- Error handling
+
+## Configuration
+
+### Fixed Values
+- Engine path: `"stockfish"` (internal/engine/engine.go)
+- Worker count: 2 (internal/processor/processor.go)
+- Queue capacity: 100 (internal/processor/queue.go)
+- Min search time: 100ms (internal/processor/processor.go)
+
+### Validation Rules
+- Player type: 1 (human) or 2 (computer)
+- Skill level: 0-20
+- Search time: 100-10000ms
+- UCI moves: 4-5 characters ([a-h][1-8][a-h][1-8][qrbn]?)
+- Undo count: 1-300
+
+## Limitations
+
+- No persistence (memory only)
+- Hardcoded Stockfish path
+- Fixed worker pool size
+- No game history beyond current session