feat: integrate Starlark/Tronbyte app support into plugin system

Add starlark-apps plugin that renders Tidbyt/Tronbyte .star apps via
Pixlet binary and integrates them into the existing Plugin Manager UI
as virtual plugins. Includes vegas scroll support, Tronbyte repository
browsing, and per-app configuration.

- Extract working starlark plugin code from starlark branch onto fresh main
- Fix plugin conventions (get_logger, VegasDisplayMode, BasePlugin)
- Add 13 starlark API endpoints to api_v3.py (CRUD, browse, install, render)
- Virtual plugin entries (starlark:<app_id>) in installed plugins list
- Starlark-aware toggle and config routing in pages_v3.py
- Tronbyte repository browser section in Plugin Store UI
- Pixlet binary download script (scripts/download_pixlet.sh)

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

plugin-repos/starlark-apps/manifest.json

@@ -0,0 +1,26 @@
+{
+  "id": "starlark-apps",
+  "name": "Starlark Apps",
+  "version": "1.0.0",
+  "author": "LEDMatrix",
+  "description": "Manages and displays Starlark (.star) apps from Tronbyte/Tidbyt community. Import widgets seamlessly without modification.",
+  "entry_point": "manager.py",
+  "class_name": "StarlarkAppsPlugin",
+  "category": "system",
+  "tags": [
+    "starlark",
+    "widgets",
+    "tronbyte",
+    "tidbyt",
+    "apps",
+    "community"
+  ],
+  "display_modes": [],
+  "update_interval": 60,
+  "default_duration": 15,
+  "dependencies": [
+    "Pillow>=10.0.0",
+    "PyYAML>=6.0",
+    "requests>=2.31.0"
+  ]
+}