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, 20 insertions, 0 deletions

diff --git a/packages/core/src/db/settings.ts b/packages/core/src/db/settings.ts
new file mode 100644
index 0000000..51d6ea2
--- /dev/null
+++ b/packages/core/src/db/settings.ts
@@ -0,0 +1,20 @@
+import { getDatabase } from "./index.js";
+
+export function getSetting(key: string): string | null {
+	const db = getDatabase();
+	const row = db.query("SELECT value FROM settings WHERE key = $key").get({ $key: key }) as { value: string } | null;
+	return row?.value ?? null;
+}
+
+export function setSetting(key: string, value: string): void {
+	const db = getDatabase();
+	db.query(
+		`INSERT INTO settings (key, value) VALUES ($key, $value)
+		 ON CONFLICT(key) DO UPDATE SET value = $value`,
+	).run({ $key: key, $value: value });
+}
+
+export function deleteSetting(key: string): void {
+	const db = getDatabase();
+	db.query("DELETE FROM settings WHERE key = $key").run({ $key: key });
+}