Add Timelog: show the timer in the tab title and simplify the code

This is the first commit of the project, at the state that runs on
timelog.minhtrannhat.com.

Changes in this state:
- Remove redundant UI text from the sidebar, timer and insights pages.
- Show the remaining time and tag in the browser tab title while a
  session runs.
- Put the shared record type and the due and end helpers in
  src/shared/record.ts.
- Remove the startup tag migration and the one-time Forest import
  script. The live data does not need them.
- Remove unused CSS, Playwright ignore rules and duplicate helpers.
- Do not track Forest CSV exports, because they contain private data.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

scripts/backup.ts

@@ -0,0 +1,23 @@
+import { mkdir } from "node:fs/promises";
+import { dirname } from "node:path";
+import { Database } from "bun:sqlite";
+
+const source = process.env.DB_PATH || "./dev.sqlite";
+const destination = Bun.argv[2];
+if (!destination) {
+  console.error("Usage: bun scripts/backup.ts /path/to/new-backup.sqlite");
+  process.exit(1);
+}
+if (await Bun.file(destination).exists()) {
+  console.error(`Backup already exists: ${destination}`);
+  process.exit(1);
+}
+
+await mkdir(dirname(destination), { recursive: true });
+const db = new Database(source);
+try {
+  db.query("VACUUM INTO ?").run(destination);
+  console.log(`SQLite backup written to ${destination}`);
+} finally {
+  db.close();
+}