feat: add problem detection framework for common problems (#2412)

Introduces a ProblemManager that detects and surfaces actionable issues
(stale config, legacy frigate-hass-card resources, slow/failed streams)
via status bar indicators and notification popups with fix actions.

docs/troubleshooting.md

@@ -2,23 +2,46 @@
 
 ## Highlighted Issues
 
-### Duplicate versions / Duplicate element registrations / `Custom element not found: advanced-camera-card`
+### Legacy dashboard resource detected
 
-If your card appears to not load anymore (but was working previously), you're
-seeing the version of the card changing between reloads, or seeing log entries
-like:
+You still have the old `frigate-hass-card.js` resource registered in your
+dashboard (and not `advanced-camera-card.js`). Having both registered causes
+duplicate element registration errors and unpredictable behavior. Symptoms
+include the card not loading, the version changing between reloads, or log
+entries like:
 
 `Failed to execute 'define' on 'CustomElementRegistry': the name "focus-trap" has already been used with this registry window`
 
-Verify that your dashboard resources contain only a single instance of the card
-(for HACS users, you should see only `/hacsfiles/advanced-camera-card/`. If you
-_also_ see `/hacsfiles/frigate-card/`, remove it, clear your caches and reload).
+To fix:
 
-Steps:
+1. Edit your dashboard (click the three-dot menu in the top right) and select
+   **Manage Resources**.
+1. Remove any entry referring to `frigate-hass-card`. You should only have a
+   single entry for `advanced-camera-card`.
+1. Optionally, delete the `frigate-hass-card` directory on your filesystem if
+   present (e.g. `$HA_PATH/www/community/frigate-hass-card`), as long as an
+   `advanced-camera-card` directory exists there too.
+1. Clear your browser cache and reload.
 
-1. Edit your dashboard -> (Three dots menu) -> `Manage Resources`. Remove any line item that refers to `frigate-hass-card`. You should only have a single row entry for `advanced-camera-card`.
-1. [Optionally] You can delete the frigate-hass-card directory on your filesystem if present, e.g. `$HA_PATH/www/community/frigate-hass-card`, as long as it has an `advanced-camera-card` directory there too.
-1. Clear all your caches.
+If you are an admin user and the card detects both resources are registered, an
+alert icon will appear in the status bar -- clicking it will display a
+notification with a button to automatically remove the legacy resource.
+
+### Configuration upgrade available
+
+If you see a notification that a configuration upgrade is available, it means
+your card configuration uses an older format that can be automatically updated.
+
+To upgrade:
+
+1. Open your Home Assistant dashboard.
+1. Click the pencil icon to enter edit mode.
+1. Click the three-dot menu on your card and choose **Edit**.
+1. In the card editor, click the **Automatic Upgrade** button at the top.
+1. Review the changes and save.
+
+If the automatic upgrade button is not visible, your configuration may already
+be up to date. Try clearing your browser cache and reloading.
 
 ### Stream does not load