Update ruff rules and document logging patterns

- Added logging-related ruff rules (G, LOG) to pyproject.toml
- Temporarily ignored G001, G002 during migration
- Created comprehensive logging patterns documentation
- Documented structured logging configuration and patterns
- Provided migration guide from standard to structured logging

This completes Phase 5.5-5.6: Update ruff rules and document logging patterns

docs/development/logging-patterns.md

@@ -0,0 +1,181 @@
+# Logging Patterns and Guidelines
+
+## Overview
+
+This document describes the logging patterns and guidelines for AITBC services. We use structured logging with `structlog` to provide consistent, parseable logs across all services.
+
+## Structured Logging Configuration
+
+### Setup
+
+Logging is configured using `structlog` in `app_logging.py`:
+
+```python
+from aitbc import get_logger
+
+logger = get_logger(__name__)
+```
+
+### Log Format
+
+Logs are output in JSON format with the following fields:
+- `timestamp` - ISO 8601 timestamp
+- `logger` - Logger name (module name)
+- `level` - Log level (INFO, WARNING, ERROR, etc.)
+- `event` - Event description
+- Additional context fields as key-value pairs
+
+### Log Levels
+
+- **DEBUG** - Detailed diagnostic information
+- **INFO** - General informational messages
+- **WARNING** - Warning messages for potentially harmful situations
+- **ERROR** - Error messages for error events
+- **CRITICAL** - Critical messages for very severe error events
+
+## Logging Patterns
+
+### Basic Logging
+
+```python
+logger.info("Event description", field1=value1, field2=value2)
+```
+
+### Request Logging
+
+Request ID correlation is automatically added by `RequestIDMiddleware`. The request ID is available in `request.state.request_id`:
+
+```python
+logger = logger.bind(request_id=request.state.request_id)
+logger.info("Processing request", method=request.method, path=request.url.path)
+```
+
+### Error Logging
+
+Always include error context when logging errors:
+
+```python
+try:
+    # operation
+except Exception as e:
+    logger.error("Operation failed", error=str(e), operation="some_operation")
+    raise
+```
+
+### Performance Logging
+
+Performance metrics are automatically logged by `PerformanceLoggingMiddleware`. Manual performance logging:
+
+```python
+import time
+
+start_time = time.perf_counter()
+# operation
+duration = time.perf_counter() - start_time
+logger.info("Operation completed", duration_ms=duration * 1000, operation="some_operation")
+```
+
+## Middleware
+
+### Request ID Middleware
+
+Adds a unique request ID to each request for correlation:
+
+- Generates or retrieves request ID from `X-Request-ID` header
+- Binds request ID to logger context
+- Adds request ID to response headers
+- Logs request start and completion
+
+### Performance Logging Middleware
+
+Tracks request timing:
+
+- Logs request duration in milliseconds
+- Adds `X-Process-Time` header to responses
+- Logs method, path, and status code
+
+## Guidelines
+
+### DO
+
+- Use structured logging with key-value pairs
+- Include relevant context in log messages
+- Use appropriate log levels
+- Log errors with exception context
+- Use request ID for correlation
+
+### DON'T
+
+- Use string formatting in log messages (use key-value pairs instead)
+- Log sensitive information (passwords, tokens, etc.)
+- Use bare `except:` clauses
+- Log at DEBUG level in production unless necessary
+- Log the same information multiple times
+
+## Examples
+
+### Good
+
+```python
+logger.info(
+    "User logged in",
+    user_id=user.id,
+    email=user.email,
+    ip_address=request.client.host,
+)
+```
+
+### Bad
+
+```python
+logging.info(f"User {user.email} logged in from {request.client.host}")
+```
+
+## Migration Guide
+
+To migrate from standard logging to structured logging:
+
+1. Replace `import logging` with `from aitbc import get_logger`
+2. Replace `logging.getLogger(__name__)` with `get_logger(__name__)`
+3. Replace f-strings with key-value pairs
+4. Update log calls to use structured format
+
+### Before
+
+```python
+import logging
+
+logger = logging.getLogger(__name__)
+logger.info(f"Processing request {request_id}")
+```
+
+### After
+
+```python
+from aitbc import get_logger
+
+logger = get_logger(__name__)
+logger.info("Processing request", request_id=request_id)
+```
+
+## Configuration
+
+Log level can be configured via environment variable or settings:
+
+```python
+from .app_logging import configure_logging
+
+configure_logging(level="INFO")  # or "DEBUG", "WARNING", "ERROR"
+```
+
+## Ruff Rules
+
+The following ruff rules are enforced for logging:
+- `G` - logging-string-format (enforce structured logging)
+- `LOG` - logging best practices
+
+Some rules are temporarily ignored during migration:
+- `G001` - logging-string-format
+- `G002` - logging-string-format
+
+These will be enforced after migration is complete.