feat(logging): implement configurable log levels via VITE_LOG_LEVEL

Add comprehensive logging configuration system with environment variable support.
Environment files now include appropriate log levels per build mode:
- Development: debug (maximum visibility)
- Production: warn (minimal noise)
- Testing: info (balanced output)

Includes smart default behavior based on platform and environment,
enhanced logger methods for level checking, and comprehensive documentation.
All existing logging calls remain backward compatible.

Closes logging configuration request

doc/logging-configuration.md

@@ -0,0 +1,117 @@
+# Logging Configuration Guide
+
+## Overview
+
+TimeSafari now supports configurable logging levels via the `VITE_LOG_LEVEL` environment variable. This allows developers to control the verbosity of console output without modifying code.
+
+## Available Log Levels
+
+| Level | Value | Description | Console Output |
+|-------|-------|-------------|----------------|
+| `error` | 0 | Errors only | Critical errors only |
+| `warn` | 1 | Warnings and errors | Warnings and errors |
+| `info` | 2 | Info, warnings, and errors | General information, warnings, and errors |
+| `debug` | 3 | All log levels | Verbose debugging information |
+
+## Environment Variable
+
+Set the `VITE_LOG_LEVEL` environment variable to control logging:
+
+```bash
+# Show only errors
+VITE_LOG_LEVEL=error
+
+# Show warnings and errors (default for production web)
+VITE_LOG_LEVEL=warn
+
+# Show info, warnings, and errors (default for development/capacitor)
+VITE_LOG_LEVEL=info
+
+# Show all log levels including debug
+VITE_LOG_LEVEL=debug
+```
+
+## Default Behavior by Platform
+
+The logger automatically selects appropriate default log levels based on your platform and environment:
+
+- **Production Web**: `warn` (warnings and errors only)
+- **Electron**: `error` (errors only - very quiet)
+- **Development/Capacitor**: `info` (info and above)
+
+## Usage Examples
+
+### Setting Log Level in Development
+
+```bash
+# In your terminal before running the app
+export VITE_LOG_LEVEL=debug
+npm run dev
+
+# Or inline
+VITE_LOG_LEVEL=debug npm run dev
+```
+
+### Setting Log Level in Production
+
+```bash
+# For verbose production logging
+VITE_LOG_LEVEL=info npm run build:web
+
+# For minimal production logging
+VITE_LOG_LEVEL=warn npm run build:web
+```
+
+### Programmatic Access
+
+The logger provides methods to check current configuration:
+
+```typescript
+import { logger } from '@/utils/logger';
+
+// Get current log level
+const currentLevel = logger.getCurrentLevel(); // 'info'
+
+// Check if a level is enabled
+const debugEnabled = logger.isLevelEnabled('debug'); // false if level < debug
+
+// Get available levels
+const levels = logger.getAvailableLevels(); // ['error', 'warn', 'info', 'debug']
+```
+
+## Database Logging
+
+Database logging continues to work regardless of console log level settings. All log messages are still stored in the database for debugging and audit purposes.
+
+## Migration Notes
+
+- **Existing code**: No changes required - logging behavior remains the same
+- **New feature**: Use `VITE_LOG_LEVEL` to override default behavior
+- **Backward compatible**: All existing logging calls work as before
+
+## Best Practices
+
+1. **Development**: Use `VITE_LOG_LEVEL=debug` for maximum visibility
+2. **Testing**: Use `VITE_LOG_LEVEL=info` for balanced output
+3. **Production**: Use `VITE_LOG_LEVEL=warn` for minimal noise
+4. **Debugging**: Temporarily set `VITE_LOG_LEVEL=debug` to troubleshoot issues
+
+## Troubleshooting
+
+### No Logs Appearing
+
+Check your `VITE_LOG_LEVEL` setting:
+```bash
+echo $VITE_LOG_LEVEL
+```
+
+### Too Many Logs
+
+Reduce verbosity by setting a lower log level:
+```bash
+VITE_LOG_LEVEL=warn
+```
+
+### Platform-Specific Issues
+
+Remember that Electron is very quiet by default. Use `VITE_LOG_LEVEL=info` to see more output in Electron builds.