fix(plugins): web mode lookups use the modes the display registered (#668)

A plugin may compute its display modes from its config: soccer-scoreboard
registers soccer_<league>_live/recent/upcoming for every custom_leagues
entry, which no manifest can list ahead of time. The display always rotated
them (_register_loaded_plugin prefers plugin.modes), but the web process
reads plugins as files, so /display/modes, the on-demand dialog and
on-demand/start with a mode and no plugin_id saw only manifests -- a custom
league's mode was missing from every list and 404'd on lookup.

- PluginStateManager.record_modes(): the controller records what it
  registered, on the loaded record (an unload or reload forgets it)
- the runtime snapshot carries it per plugin as "modes" (bounded), and
  PluginRuntimeView.display_modes() reports it only while live
- PluginCatalog takes a runtime_source; get_plugin_display_modes and
  find_plugin_for_mode prefer the live modes, falling back to the manifest
  when the display is stopped or has not loaded the plugin. The view is read
  at most once a second, so a listing is one read, not one per plugin.

No manifest or plugin change needed.

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

web_interface/app.py

@@ -159,10 +159,18 @@ schema_manager = SchemaManager(
 # saves reach the running plugins through the display's config watcher; what
 # the display knows at run time (health, metrics, errors, current mode) it
 # publishes to the shared cache. See docs/ARCHITECTURE.md.
+def _catalog_runtime_view():
+    """The display's runtime view, for the catalog's mode lookups. Imported
+    on call, as the startup reconciliation below imports it."""
+    from web_interface.blueprints.api_v3 import _plugin_runtime_view
+    return _plugin_runtime_view()
+
+
 plugin_catalog = PluginCatalog(
     plugins_dir=plugins_dir,
     config_manager=config_manager,
     schema_manager=schema_manager,
+    runtime_source=_catalog_runtime_view,
 )
 
 # Initialize operation queue for plugin operations