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>

test/web_interface/test_api_v3_unhandled_errors.py

@@ -122,8 +122,22 @@ def test_credentials_are_redacted_from_the_detail(client):
     assert body["details"].startswith("RuntimeError: forced failure")
 
 
-def test_a_client_error_keeps_its_own_status(client):
+def _raise_415():
+    raise UnsupportedMediaType(
+        "Did not attempt to load JSON data because the request Content-Type "
+        "was not 'application/json'.")
+
+
+# An api_v3 route raising a 415 from inside. No route does that on its own
+# any more (the asset delete route, which used to, now reads its body with
+# get_json(silent=True)), so one route's view is swapped for one that does;
+# the endpoint stays api_v3's, so its error handler is the one that answers.
+_SWAPPED_ENDPOINT = "api_v3.delete_plugin_asset"
+
+
+def test_a_client_error_keeps_its_own_status(client, monkeypatch):
     """HTTPExceptions subclass Exception; a 415 must not become a 500."""
+    monkeypatch.setitem(client.application.view_functions, _SWAPPED_ENDPOINT, _raise_415)
     resp = client.post("/api/v3/plugins/assets/delete", data="not json",
                        content_type="text/plain")
     assert resp.status_code == 415
@@ -151,8 +165,9 @@ class TestInTheRealApp:
         assert resp.get_json() == EXPECTED
 
     def test_client_errors_read_the_same_as_the_global_handler(
-            self, web_app, exploding_managers):
+            self, web_app, exploding_managers, monkeypatch):
         """The blueprint's 4xx shape must not drift from app.py's."""
+        monkeypatch.setitem(web_app.app.view_functions, _SWAPPED_ENDPOINT, _raise_415)
         resp = web_app.app.test_client().post(
             "/api/v3/plugins/assets/delete", data="not json",
             content_type="text/plain")