feat: implement production-ready features from improvement plan phase 2.5 & 2.6

Phase 2.5: Fix Foundation (CRITICAL)
- Fixed 4 failing tests by adding cache attribute to mock_client fixture
- Created comprehensive cache tests for Pages endpoint (test_pages_cache.py)
- Added missing dependencies: pydantic[email] and aiohttp to core requirements
- Updated requirements.txt with proper dependency versions
- Achieved 82.67% test coverage with 454 passing tests

Phase 2.6: Production Essentials
- Implemented structured logging (wikijs/logging.py)
  * JSON and text log formatters
  * Configurable log levels and output destinations
  * Integration with client operations

- Implemented metrics and telemetry (wikijs/metrics.py)
  * Request tracking with duration, status codes, errors
  * Latency percentiles (min, max, avg, p50, p95, p99)
  * Error rate calculation
  * Thread-safe metrics collection

- Implemented rate limiting (wikijs/ratelimit.py)
  * Token bucket algorithm for request throttling
  * Per-endpoint rate limiting support
  * Configurable timeout handling
  * Burst capacity management

- Created SECURITY.md policy
  * Vulnerability reporting procedures
  * Security best practices
  * Response timelines
  * Supported versions

Documentation
- Added comprehensive logging guide (docs/logging.md)
- Added metrics and telemetry guide (docs/metrics.md)
- Added rate limiting guide (docs/rate_limiting.md)
- Updated README.md with production features section
- Updated IMPROVEMENT_PLAN_2.md with completed checkboxes

Testing
- Created test suite for logging (tests/test_logging.py)
- Created test suite for metrics (tests/test_metrics.py)
- Created test suite for rate limiting (tests/test_ratelimit.py)
- All 454 tests passing
- Test coverage: 82.67%

Breaking Changes: None
Dependencies Added: pydantic[email], email-validator, dnspython

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

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

tests/test_ratelimit.py

@@ -0,0 +1,73 @@
+"""Tests for rate limiting functionality."""
+import time
+import pytest
+from wikijs.ratelimit import RateLimiter, PerEndpointRateLimiter
+
+
+def test_rate_limiter_init():
+    """Test rate limiter initialization."""
+    limiter = RateLimiter(requests_per_second=10.0)
+
+    assert limiter.rate == 10.0
+    assert limiter.burst == 10
+
+
+def test_rate_limiter_acquire():
+    """Test acquiring tokens."""
+    limiter = RateLimiter(requests_per_second=100.0)
+
+    # Should be able to acquire immediately
+    assert limiter.acquire(timeout=1.0) is True
+
+
+def test_rate_limiter_burst():
+    """Test burst behavior."""
+    limiter = RateLimiter(requests_per_second=10.0, burst=5)
+
+    # Should be able to acquire up to burst size
+    for _ in range(5):
+        assert limiter.acquire(timeout=0.1) is True
+
+
+def test_rate_limiter_timeout():
+    """Test timeout behavior."""
+    limiter = RateLimiter(requests_per_second=1.0)
+
+    # Exhaust tokens
+    assert limiter.acquire(timeout=1.0) is True
+
+    # Next acquire should timeout quickly
+    assert limiter.acquire(timeout=0.1) is False
+
+
+def test_rate_limiter_reset():
+    """Test rate limiter reset."""
+    limiter = RateLimiter(requests_per_second=1.0)
+
+    # Exhaust tokens
+    limiter.acquire()
+
+    # Reset
+    limiter.reset()
+
+    # Should be able to acquire again
+    assert limiter.acquire(timeout=0.1) is True
+
+
+def test_per_endpoint_rate_limiter():
+    """Test per-endpoint rate limiting."""
+    limiter = PerEndpointRateLimiter(default_rate=10.0)
+
+    # Set different rate for specific endpoint
+    limiter.set_limit("/api/special", 5.0)
+
+    # Should use endpoint-specific rate
+    assert limiter.acquire("/api/special", timeout=1.0) is True
+
+
+def test_per_endpoint_default_rate():
+    """Test default rate for endpoints."""
+    limiter = PerEndpointRateLimiter(default_rate=100.0)
+
+    # Should use default rate for unknown endpoint
+    assert limiter.acquire("/api/unknown", timeout=1.0) is True