Add health check endpoints and automatic language detection

Health Check Features (Item 12):
- Added /health endpoint for basic health monitoring
- Added /health/detailed for comprehensive component status
- Added /health/ready for Kubernetes readiness probes
- Added /health/live for liveness checks
- Frontend health monitoring with auto-recovery
- Clear stuck requests after 60 seconds
- Visual health warnings when service is degraded
- Monitoring script for external health checks

Automatic Language Detection (Item 13):
- Added "Auto-detect" option in source language dropdown
- Whisper automatically detects language when auto-detect is selected
- Shows detected language in UI after transcription
- Updates language selector with detected language
- Caches transcriptions with correct detected language

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

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

templates/index.html

@@ -133,6 +133,7 @@
                     </div>
                     <div class="card-body">
                         <select id="sourceLanguage" class="form-select language-select mb-3">
+                            <option value="auto">Auto-detect</option>
                             {% for language in languages %}
                             <option value="{{ language }}">{{ language }}</option>
                             {% endfor %}