Move preview button to per-slot in edit form, remove card dropdown

- Preview button always visible next to Variables for each template slot
- Remove \n\n prefix from video_warning default value
- Use conditional {% if video_warning %} with blank line in templates
- Fix all .jinja2 files and inline defaults to match
- Add SVG favicon (camera + notification dot)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/server/src/immich_watcher_server/api/template_configs.py

@@ -67,7 +67,7 @@ _SAMPLE_CONTEXT = {
     "removed_assets": ["asset-id-1", "asset-id-2"],
     "people": ["Alice", "Bob"],
     "shared": True,
-    "video_warning": "\n\n⚠️ Note: Videos may not be sent due to Telegram's 50 MB file size limit.",
+    "video_warning": "⚠️ Note: Videos may not be sent due to Telegram's 50 MB file size limit.",
     # Rename fields (always present, empty for non-rename events)
     "old_name": "Old Album",
     "new_name": "New Album",