feat(ombi): Add Ombi PALDRA integration for request management

- Add OmbiRetriever extending ArrRetriever for PALDRA compliance
- Add OmbiClient for low-level Ombi API communication
- Add getOmbiInstances() to config.js following multi-instance pattern
- Register Ombi in PALDRA registry with Ombi-specific methods
- Add external ID matching (TMDB/TVDB/IMDB) to Ombi requests
- Update DownloadMatcher to be async and enrich downloads with Ombi links
- Add getOmbiLink/getOmbiSearchLink helpers to DownloadAssembler
- Implement new service icon layout (Ombi + Sonarr/Radarr icons)
- Add CSS styling for service icons
- Update dashboard routes to include Ombi configuration
- Extend OpenAPI with Ombi tag and NormalizedDownload properties
- Update documentation (README, ARCHITECTURE, SECURITY, CHANGELOG)
- Add Ombi configuration to .env.sample

.env.sample

@@ -157,6 +157,12 @@ RADARR_INSTANCES=[{"name":"main","url":"https://radarr.example.com","apiKey":"yo
 # RADARR_URL=https://radarr.example.com
 # RADARR_API_KEY=your-radarr-api-key
 
+# =============================================================================
+# OMBI (Request Management - Optional)
+# =============================================================================
+OMBI_URL=https://ombi.example.com
+OMBI_API_KEY=your-ombi-api-key-here
+
 # =============================================================================
 # NOTES
 # =============================================================================