refactor: comprehensive codebase review — security, performance, quality, UX

Security:
- Fix NUT protocol command injection (validate names against safe regex)
- Enable Jinja2 autoescape=True to prevent HTML injection via external data
- Add WebhookProviderConfig validation model

Performance:
- Shared aiohttp.ClientSession singleton (replaces 40+ per-request sessions)
- Fix 4 N+1 queries with batch IN loads (poller, scheduler, memory, broadcast)
- asyncio.gather for Gitea commands and notification dispatcher
- Add DB indexes on NotificationTrackerState.tracker_id, CommandTrackerListener
- LRU cache for compiled Jinja2 templates
- Daily EventLog cleanup job (90-day retention)
- 30s HTTP timeout on all external calls
- GROUP BY for target type counts (replaces 7 sequential queries)

Code quality:
- Extract get_owned_entity() helper (replaces 11 duplicate functions)
- Extract slot_helpers.py (load_slots, save_slots, render_template_preview)
- Extract command_utils.py (tracker lookup, last event, collection IDs)
- Extract http_session.py (shared session lifecycle)
- Provider connection validation dedup (3x → 1 helper)
- Command dispatch tables replacing if/elif chains
- Album+links fetch helper (fetch_albums_with_links)
- Provider dispatch polymorphism (list_provider_collections)
- Immutable _enrich_assets (no longer mutates in-place)
- Fix _format_assets return type + handler unpacking

Frontend:
- Fix 18+ hardcoded English strings → t() with new i18n keys (en + ru)
- Mobile "More" nav panel with provider filter and search
- Shared Button.svelte component (4 variants, 2 sizes)
- Shared ErrorBanner.svelte component (8 pages updated)
- SvelteKit goto() replacing window.location.href
- Dashboard grid fixed for 4 cards, paginator opacity consistency

Functionality:
- max_instances=1 on scheduler jobs (prevents duplicate events)
- Webhook provider in watcher (prevents error spam)
- Fix stale SQLModel reference in poller
- Gitea get_repo() direct API call

.gitea/workflows/release.yml

@@ -43,6 +43,17 @@ jobs:
           cache-from: type=registry,ref=${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:buildcache
           cache-to: type=registry,ref=${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:buildcache,mode=max
 
+      - name: Trigger Portainer redeploy
+        continue-on-error: true
+        run: |
+          if [ -n "${{ secrets.DOCKER_REDEPLOY_WEBHOOK_URL }}" ]; then
+            echo "Triggering Portainer redeploy..."
+            curl -sf -X POST "${{ secrets.DOCKER_REDEPLOY_WEBHOOK_URL }}" \
+              --max-time 30 || echo "::warning::Portainer webhook failed"
+          else
+            echo "DOCKER_REDEPLOY_WEBHOOK_URL not set — skipping auto-deploy"
+          fi
+
       - name: Generate changelog
         id: changelog
         run: |
@@ -56,7 +67,29 @@ jobs:
 
       - name: Create Gitea Release
         run: |
-          BODY=$(cat /tmp/changelog.txt | python3 -c "import sys,json; print(json.dumps(sys.stdin.read()))")
+          if [ -f RELEASE_NOTES.md ]; then
+            export RELEASE_NOTES=$(cat RELEASE_NOTES.md)
+            echo "Found RELEASE_NOTES.md"
+          else
+            export RELEASE_NOTES=""
+            echo "No RELEASE_NOTES.md found"
+          fi
+
+          BODY=$(python3 -c "
+          import json, os, sys
+
+          release_notes = os.environ.get('RELEASE_NOTES', '')
+          changelog = open('/tmp/changelog.txt').read().strip()
+
+          sections = []
+          if release_notes.strip():
+              sections.append(release_notes.strip())
+          if changelog:
+              sections.append('## Changelog\n\n' + changelog)
+
+          print(json.dumps('\n\n'.join(sections)))
+          ")
+
           curl -s -X POST \
             "https://${{ env.REGISTRY }}/api/v1/repos/${{ env.IMAGE_NAME }}/releases" \
             -H "Authorization: token ${{ secrets.RELEASE_TOKEN }}" \