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, 29 insertions, 0 deletions

diff --git a/packages/core/src/db/index.ts b/packages/core/src/db/index.ts
index 818aff0..2992708 100644
--- a/packages/core/src/db/index.ts
+++ b/packages/core/src/db/index.ts
@@ -74,6 +74,35 @@ export function getDatabase(): Database {
 		updated_at  INTEGER NOT NULL
 	)`);
 
+	_db.run(`CREATE TABLE IF NOT EXISTS tabs (
+		id          TEXT PRIMARY KEY,
+		title       TEXT NOT NULL,
+		key_id      TEXT,
+		model_id    TEXT,
+		status      TEXT NOT NULL DEFAULT 'idle',
+		is_open     INTEGER NOT NULL DEFAULT 1,
+		position    INTEGER NOT NULL DEFAULT 0,
+		created_at  INTEGER NOT NULL,
+		updated_at  INTEGER NOT NULL
+	)`);
+
+	_db.run(`CREATE TABLE IF NOT EXISTS messages (
+		id           TEXT PRIMARY KEY,
+		tab_id       TEXT NOT NULL REFERENCES tabs(id),
+		seq          INTEGER NOT NULL,
+		role         TEXT NOT NULL,
+		content_json TEXT NOT NULL,
+		thinking     TEXT,
+		created_at   INTEGER NOT NULL
+	)`);
+
+	_db.run(`CREATE INDEX IF NOT EXISTS idx_messages_tab ON messages(tab_id, seq)`);
+
+	_db.run(`CREATE TABLE IF NOT EXISTS settings (
+		key   TEXT PRIMARY KEY,
+		value TEXT NOT NULL
+	)`);
+
 	return _db;
 }