Status LEDs, image model selection, backup restore, provider test, monthly versions

- Sidebar: three status LEDs (server, models, MCP) with an overview popover (/api/status)
- Images: preview stage, purpose-based model choice and reference images
  (Nano Banana Pro edit refines the chosen preview)
- Settings: restore a stored or uploaded backup (staged, applied on restart)
- Provider form: test connection; saving or reloading re-checks the status at once
- opencode Zen/Go: send x-opencode-session with a stable id per conversation
- Releases are named vYYYYMM-NNNNN; scripts/release.sh numbers, tags, builds and publishes
- Fix: backups made in the same second no longer overwrite each other

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.env.example

@@ -27,7 +27,7 @@ OPENROUTER_API_KEY=
 # Time zone for automations (cron schedules) and timestamps, e.g. Europe/Berlin
 TZ=UTC
 
-# Image version for docker-compose.release.yml (e.g. 0.1.0); default: latest
+# Image version for docker-compose.release.yml (e.g. v202611-00001); default: latest
 CODECRAFT_VERSION=latest
 
 # Log format: empty for text, "json" for one JSON object per line