docs(store): describe the monorepo registry and the store UI as they are

- PLUGIN_STORE_GUIDE: the Plugin Store is a section of the Plugin
  Manager tab; URL installs are "Install from GitHub" -> "Install Single
  Plugin"; bulk update exists (Check & Update All) plus opt-in weekly
  auto-update; PluginStoreManager() defaults to plugins/, so the Python
  examples pass plugin-repos; registry plugins are downloaded (GitHub API,
  ZIP fallback), not cloned; updates compare version with latest_version.
- PLUGIN_REGISTRY_SETUP_GUIDE: replace the per-plugin-repo + tag
  walkthrough with a short page on the monorepo registry (plugin_path,
  latest_version, update_registry.py) that points at the monorepo's own
  SUBMISSION.md. Drops the reference to the deleted
  PLUGIN_IMPLEMENTATION_SUMMARY.md and setup_plugin_repos.py.
- plugin_registry_template.json: use the real entry shape.
- PLUGIN_QUICK_REFERENCE: automatic background updates exist (opt-in);
  registry example and publishing steps use the monorepo, not tags.
- PLUGIN_DEVELOPMENT_GUIDE: tags/releases are not read by the store.

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

docs/plugin_registry_template.json

@@ -1,7 +1,6 @@
 {
   "version": "1.0.0",
-  "last_updated": "2025-01-09T12:00:00Z",
-  "description": "Official plugin registry for LEDMatrix",
+  "last_updated": "2026-09-03",
   "plugins": [
     {
       "id": "hello-world",
@@ -10,86 +9,32 @@
       "author": "ChuckBuilds",
       "category": "example",
       "tags": ["example", "tutorial", "beginner"],
-      "repo": "https://github.com/ChuckBuilds/LEDMatrix",
+      "repo": "https://github.com/ChuckBuilds/ledmatrix-plugins",
       "branch": "main",
-      "path": "plugins/hello-world",
-      "versions": [
-        {
-          "version": "1.0.0",
-          "ledmatrix_min_version": "2.0.0",
-          "released": "2025-01-09",
-          "download_url": "https://github.com/ChuckBuilds/LEDMatrix/archive/refs/heads/main.zip",
-          "changelog": "Initial release"
-        }
-      ],
+      "plugin_path": "plugins/hello-world",
       "stars": 0,
       "downloads": 0,
-      "last_updated": "2025-01-09",
+      "last_updated": "2026-09-03",
       "verified": true,
-      "documentation": "https://github.com/ChuckBuilds/LEDMatrix/blob/main/plugins/hello-world/README.md"
+      "screenshot": "",
+      "latest_version": "1.0.0"
     },
     {
-      "id": "clock-simple",
-      "name": "Simple Clock",
-      "description": "A clean, simple clock display with date and time",
-      "author": "ChuckBuilds",
-      "category": "time",
-      "tags": ["clock", "time", "date"],
-      "repo": "https://github.com/ChuckBuilds/LEDMatrix",
+      "id": "my-third-party-plugin",
+      "name": "My Third-Party Plugin",
+      "description": "A plugin kept in its own repository (empty plugin_path)",
+      "author": "YourName",
+      "category": "custom",
+      "tags": ["example"],
+      "repo": "https://github.com/YourName/ledmatrix-my-third-party-plugin",
       "branch": "main",
-      "path": "plugins/clock-simple",
-      "versions": [
-        {
-          "version": "1.0.0",
-          "ledmatrix_min_version": "2.0.0",
-          "released": "2025-01-09",
-          "download_url": "https://github.com/ChuckBuilds/LEDMatrix/archive/refs/heads/main.zip",
-          "changelog": "Initial release"
-        }
-      ],
+      "plugin_path": "",
       "stars": 0,
       "downloads": 0,
-      "last_updated": "2025-01-09",
-      "verified": true,
-      "documentation": "https://github.com/ChuckBuilds/LEDMatrix/blob/main/plugins/clock-simple/README.md"
-    }
-  ],
-  "categories": [
-    {
-      "id": "time",
-      "name": "Time & Clocks",
-      "description": "Clock displays, timers, and time-related plugins"
-    },
-    {
-      "id": "sports",
-      "name": "Sports",
-      "description": "Scoreboards, schedules, and sports statistics"
-    },
-    {
-      "id": "weather",
-      "name": "Weather",
-      "description": "Weather forecasts and conditions"
-    },
-    {
-      "id": "finance",
-      "name": "Finance",
-      "description": "Stock tickers, crypto, and market data"
-    },
-    {
-      "id": "entertainment",
-      "name": "Entertainment",
-      "description": "Games, animations, and media displays"
-    },
-    {
-      "id": "example",
-      "name": "Examples & Tutorials",
-      "description": "Example plugins for learning"
-    },
-    {
-      "id": "custom",
-      "name": "Custom",
-      "description": "Unique and miscellaneous displays"
+      "last_updated": "2026-09-03",
+      "verified": false,
+      "screenshot": "",
+      "latest_version": "1.0.0"
     }
   ]
 }
-