feat: complete Phase 3 - Domain Modeling & Data Layer

Implements comprehensive type system, runtime validation, API client,
and testing infrastructure for CS2.WTF.

TypeScript Interfaces (src/lib/types/):
- Match.ts: Match, MatchPlayer, MatchListItem types
- Player.ts: Player, PlayerMeta, PlayerProfile types
- RoundStats.ts: Round economy and performance data
- Weapon.ts: Weapon statistics with hit groups (HitGroup, WeaponType enums)
- Message.ts: Chat messages with filtering support
- api.ts: API responses, errors, and APIException class
- Complete type safety with strict null checks

Zod Schemas (src/lib/schemas/):
- Runtime validation for all data models
- Schema parsers with safe/unsafe variants
- Special handling for backend typo (looses → losses)
- Share code validation regex
- CS2-specific validations (rank 0-30000, MR12 rounds)

API Client (src/lib/api/):
- client.ts: Axios-based HTTP client with error handling
  - Request cancellation support (AbortController)
  - Automatic retry logic for transient failures
  - Timeout handling (10s default)
  - Typed APIException errors
- players.ts: Player endpoints (profile, meta, track/untrack, search)
- matches.ts: Match endpoints (parse, details, weapons, rounds, chat, search)
- Zod validation on all API responses

MSW Mock Handlers (src/mocks/):
- fixtures.ts: Comprehensive mock data for testing
- handlers/players.ts: Mock player API endpoints
- handlers/matches.ts: Mock match API endpoints
- browser.ts: Browser MSW worker for development
- server.ts: Node MSW server for Vitest tests
- Realistic responses with delays and pagination
- Safe integer IDs to avoid precision loss

Configuration:
- .env.example: Complete environment variable documentation
- src/vite-env.d.ts: Vite environment type definitions
- All strict TypeScript checks passing (0 errors, 0 warnings)

Features:
- Cancellable requests for search (prevent race conditions)
- Data normalization (backend typo handling)
- Comprehensive error types (NetworkError, Timeout, etc.)
- Share code parsing and validation
- Pagination support for players and matches
- Mock data for offline development and testing

Build Status: ✓ Production build successful
Type Check: ✓ 0 errors, 0 warnings
Lint: ✓ All checks passed
Phase 3 Completion: 100%

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

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

src/mocks/server.ts

@@ -0,0 +1,39 @@
+import { setupServer } from 'msw/node';
+import { beforeAll, afterEach, afterAll } from 'vitest';
+import { handlers } from './handlers';
+
+/**
+ * MSW Server
+ * Used for mocking API requests in Node.js (tests)
+ */
+
+/**
+ * Create MSW server for testing
+ */
+export const server = setupServer(...handlers);
+
+/**
+ * Setup server for tests
+ * Call this in test setup files (e.g., vitest.setup.ts)
+ */
+export const setupMockServer = () => {
+	// Start server before all tests
+	beforeAll(() => {
+		server.listen({ onUnhandledRequest: 'bypass' });
+	});
+
+	// Reset handlers after each test
+	afterEach(() => {
+		server.resetHandlers();
+	});
+
+	// Close server after all tests
+	afterAll(() => {
+		server.close();
+	});
+};
+
+/**
+ * Default export
+ */
+export default server;