fix(hermes): show active provider and wire add/enable/remove actions

Switching a Hermes provider previously only fired a toast because the frontend treated Hermes as non-additive (unlike backend AppType::is_additive_mode, which lists OpenCode | OpenClaw | Hermes) and relied on the unused is_current DB flag for highlighting. Align the UI model with the backend:

- Include Hermes in ProviderActions' isAdditiveMode so the main button switches between "Add" and "Remove".
- Drive the "current" highlight from model.provider (via useHermesModelConfig) instead of the DB is_current field; model.provider is Hermes's real SSOT for the active provider.
- Reuse OpenClaw's set-as-default button slot to expose an "Enable" action on Hermes that calls switchProvider, so providers already in config can be activated without re-adding. switch_normal + apply_switch_defaults already atomically update custom_providers and model.provider, so no backend change is needed.
- Invalidate liveProviderIds + modelConfig + health in parallel after add/update/delete/switch via a new invalidateHermesProviderCaches helper, replacing four copies of three sequential awaits.

src/App.tsx

@@ -1021,7 +1021,11 @@ function App() {
                       }
                       onCreate={() => setIsAddOpen(true)}
                       onSetAsDefault={
-                        activeApp === "openclaw" ? setAsDefaultModel : undefined
+                        activeApp === "openclaw"
+                          ? setAsDefaultModel
+                          : activeApp === "hermes"
+                            ? switchProvider
+                            : undefined
                       }
                     />
                   </motion.div>