fix(dashboard): lazy-init useMobileKeyboard so remount has no stale render

When ChatView remounted (e.g. tab switch with keyboard still up), the
hook started with keyboardOpen=false and corrected itself only after
the effect ran. That single stale-state render briefly unhid the
executor status bar, which appeared as a blank pane covering half the
input box before the next state update settled it.

useState initializers now call getKeyboardMetrics() lazily on first
render so the very first paint already reflects the live keyboard
state.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/settings-reference.md

@@ -38,7 +38,7 @@ Defaults from `DEFAULT_GLOBAL_SETTINGS`; key scope from `GLOBAL_SETTINGS_KEYS`.
 | `defaultModelId` | `string` | `undefined` | Default AI model ID. |
 | `fallbackProvider` | `string` | `undefined` | Fallback provider when the primary default model hits transient provider failures. |
 | `fallbackModelId` | `string` | `undefined` | Fallback model ID (must pair with `fallbackProvider`). |
-| `defaultThinkingLevel` | `"off" \| "minimal" \| "low" \| "medium" \| "high"` | `undefined` | Default reasoning effort for AI sessions. |
+| `defaultThinkingLevel` | `"off" \| "minimal" \| "low" \| "medium" \| "high"` | `undefined` | Default reasoning effort for AI sessions. If a provider/runtime rejects simultaneous `thinking` and `reasoning_effort` parameters, Fusion retries without the explicit thinking override instead of failing the run. |
 | `ntfyEnabled` | `boolean` | `false` | Enable ntfy push notifications. |
 | `ntfyTopic` | `string` | `undefined` | ntfy topic name. |
 | `ntfyBaseUrl` | `string` | `undefined` | Optional custom ntfy server base URL (must use `http://` or `https://`). If blank/unset, Fusion uses `https://ntfy.sh` for both runtime and test notifications. |