desktop: fix provider switch model selector real-time update
When switching providers via CliLoginProviderSettings login panels
(NVIDIA, OpenRouter, OpenAI, OpenCode, Local), the settingsStore's
activeProviderId/activeProviderName were never updated, causing the
conversation model's provider badge to stay stale until a full app
restart.
Fixes:
- cliAuthStore: call settingsStore.syncFromConfig() after every save
(saveNvidiaApiKey, saveOpenRouterApiKey, saveOpenAIApiKey,
saveOpenCodeApiKey, saveLocalModelConfig, setAuthProvider,
clearAuth)
- settingsStore: add syncFromConfig() action that re-reads
~/.claude.json and syncs activeProviderId/activeProviderName
- settingsStore: add setActiveProvider() for optimistic UI updates
- settingsStore.fetchAll(): fallback to deriving provider info from
config.authProvider when both direct API fetch and sidecar fail
- ModelSelector: add fallback path when availableModels is empty
(local provider, fetch f…
