feat: analysis providers, settings UI, song search, WAV duration fix

- Multi-provider AI analysis (Anthropic, OpenAI, Ollama, Algorithmic)
- server-only guards on all provider files; client bundle fix
- /settings page with provider status, Ollama model picker, preferences
- Song search box on /analyze replacing raw MBID input (debounced, keyboard nav)
- Auto-register song via MusicBrainz on POST /api/tracks (no more 404)
- Fix WAV duration bug: last section songEnd was double-counting elapsed time
- Registry sync comment updated for self-hosted HTTPS git servers

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/registry/sync.ts

@@ -1,14 +1,18 @@
 /**
  * Git Registry Sync
  *
- * Pulls CTP files from a remote GitHub repository (the "community registry")
- * and upserts them into the local database.
+ * Pulls CTP files from a remote git repository (the "community registry")
+ * served over HTTPS. Compatible with any self-hosted git server
+ * (Gitea, Forgejo, GitLab CE, Gogs, etc.) or any public git host.
  *
  * The registry repo is expected to contain CTP JSON files at:
  *   <repo-root>/<artist-initial>/<artist-slug>/<recording-mbid>.ctp.json
  *
  * Configuration:
- *   REGISTRY_REPO — GitHub repo URL, e.g. https://github.com/org/clicktrack-registry
+ *   REGISTRY_REPO — HTTPS URL of the registry repo,
+ *                   e.g. https://git.yourdomain.com/org/clicktrack-registry
+ *                   To authenticate, embed credentials in the URL:
+ *                   https://user:token@git.yourdomain.com/org/clicktrack-registry
  *   REGISTRY_BRANCH — branch to pull from (default: main)
  */