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]>

Dockerfile.api

@@ -0,0 +1,11 @@
+FROM oven/bun:1.4.2
+WORKDIR /app
+COPY package.json bun.lock ./
+RUN bun install --frozen-lockfile --production
+COPY src/api ./src/api
+COPY src/shared ./src/shared
+COPY scripts/backup.ts ./scripts/backup.ts
+RUN mkdir -p /data && chown bun:bun /data
+USER bun
+EXPOSE 3001
+CMD ["bun", "src/api/server.ts"]