feat: tab system with per-tab agents, DB persistence, and DaisyUI tabs-lift UI

- Add tabs, messages, and settings tables to SQLite database
- Backend: refactor AgentManager to manage per-tab Agent instances via Map<tabId, TabAgent>
- Backend: WebSocket events tagged with tabId for multiplexing
- Backend: tab CRUD routes (create, list, update, archive, messages)
- Backend: persist user and assistant messages to DB during chat
- Frontend: new tabStore replaces single chatStore with multi-tab reactive state
- Frontend: TabBar component using DaisyUI tabs-lift style with status dots
- Frontend: Settings sidebar panel for title generation model selection
- Frontend: wire ChatPanel, ChatInput, Header to use tabStore
- Fix HMR listener accumulation via wsClient.clearCallbacks()
- Delete old single-chat chatStore (chat.svelte.ts)

1 files changed, 5 insertions, 0 deletions

diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
index b1e2e14..3b49de9 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -32,3 +32,8 @@ export * from "./credentials/index.js";
 
 // Database
 export { getDatabase, closeDatabase, getDatabasePath } from "./db/index.js";
+
+// Tabs & Messages
+export { type TabRow, createTab, getTab, listOpenTabs, updateTabTitle, updateTabModel, updateTabStatus, archiveTab } from "./db/tabs.js";
+export { type MessageRow, appendMessage, updateMessage, getMessagesForTab, clearMessagesForTab } from "./db/messages.js";
+export { getSetting, setSetting, deleteSetting } from "./db/settings.js";