fix(web): plugin dir resolver in routes, nmcli AP detection, daemon config reload, upload safety, BDF preview (#655)

* fix(web): plugin dir resolver in routes, nmcli AP detection, daemon config reload, upload safety

- Route plugin lookups (installed list, update, recorded version, config
  form, web UI pages) through the plugin manager's resolver so plugins in
  ledmatrix-<id> directories work.
- Captive-portal detection also sees the nmcli fallback AP (cached).
- WiFi monitor daemon re-reads wifi_config.json when its mtime changes.
- Drop the AP check in disconnect_from_network that could never fire.
- LED status file per WiFiManager; config path falls back to this checkout.
- BDF font preview via src.common.bdf_font.
- Asset uploads validate every file before saving; metadata and calendar
  credentials written atomically; no absolute path in the response;
  asset delete answers 400 for a missing body.
- Coerce string booleans in plugin toggle, on-demand start and AP force.
- SSE broadcaster clears its thread handle before exiting.
- start.py log filter handles every exc_info form.
- Cleanups: unused plugins/fonts partial work, duplicate backup catch-alls,
  raw-config error helper, update-route tidy, redundant imports.

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

* fix(web): request BDF font previews now that the server renders them

The Fonts tab skipped the preview request for .bdf files because the server
used to refuse them; /fonts/preview now draws BDF with the shared loader.

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

* fix(web): take the update route's plugin directory from a directory listing

CodeQL flagged the path built from the request's plugin_id (the id was
already validated with safe_path_component, which CodeQL doesn't model; the
same flow on main is alerts 738/739). The directory is now the entry of
plugins_dir matched by name, so nothing built from user input reaches the
filesystem; an id with nothing installed goes to the store manager, which
reports it not found as before.

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

* fix(web): read the blueprint's plugin_manager defensively in _plugin_directory

_get_plugin_version now goes through _plugin_directory, which read
api_v3.plugin_manager directly; the attribute exists only once the app sets
it, so test_path_traversal_guards::test_a_real_manifest_is_read failed
when run on its own (order-dependent in the full suite).

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

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

web_interface/blueprints/api_v3/__init__.py

@@ -170,9 +170,16 @@ def _get_plugin_version(plugin_id: str) -> str:
     that arrived in a request body, so the name is validated here rather
     than relying on each of them to have done it.
     """
-    manifest_path = resolve_under(
-        api_v3.plugin_store_manager.plugins_dir, plugin_id, "manifest.json"
-    )
+    # The resolver first: a plugin installed as ledmatrix-<id>, or whose
+    # directory is named differently from its manifest id, is not at
+    # plugins_dir/<id>, and recording '' as its version hid that it worked.
+    plugin_dir = _plugin_directory(plugin_id)
+    if plugin_dir is not None:
+        manifest_path = plugin_dir / "manifest.json"
+    else:
+        manifest_path = resolve_under(
+            api_v3.plugin_store_manager.plugins_dir, plugin_id, "manifest.json"
+        )
     if manifest_path is None:
         logger.warning("[PluginVersion] Rejected unsafe plugin id %r", plugin_id)
         return ''
@@ -1420,9 +1427,11 @@ def _plugin_directory(plugin_id: str) -> Optional[Path]:
     is no fallback to the legacy plugins/ directory: the loader never scans
     it, so a plugin found only there is one that never runs.
     """
-    if not api_v3.plugin_manager:
+    # getattr: the blueprint only has plugin_manager once the app has set it.
+    manager = getattr(api_v3, 'plugin_manager', None)
+    if not manager:
         return None
-    plugin_dir = api_v3.plugin_manager.get_plugin_directory(plugin_id)
+    plugin_dir = manager.get_plugin_directory(plugin_id)
     if not plugin_dir or not Path(plugin_dir).exists():
         return None
     return Path(plugin_dir)