Release cadence: at least one tag per day, small and stable #351

Why

Releases wait until a large batch is done (e.g. #152 for v0.2.0), so users and teammates see changes late and each release is big and risky. Ship small and often instead.

Proposal: at least one tag per day

• Cadence: at least one tag every day. Each tag packages whatever was merged to main that day, at a fixed time (proposed: evening Asia/Shanghai). No merged change since the last tag means skip; the point is a steady rhythm, not empty tags.
• Versioning: patch bump (v0.2.x) for fixes and small features; minor bump (v0.3.0) only for a notable new capability. Core ds-bot and plugin package versions are bumped only when their own contents change, as in Prepare the FlyBot v0.2.0 product release #152.
• Mechanics: reuse the existing tag-triggered release workflow and the per-PR changelog fragments; the daily tag assembles them into a changelog section. No new release tooling in the first version.
• Stability first: tag only a main tip where CI is green. If main is red, fix or revert first; a missed day is fine, a broken tag is not.
• One headline per release: a one-line summary plus a short screen recording when there is a visible change. This doubles as lightweight announcement (see docs(timeline): add a screen-recording demo at the top of the Timeline plugin docs #350 for recordings).

Pre-tag checklist

1. main tip CI green; no unreviewed merges (Codex review done per team rule).
2. Changelog fragments consumed and the section reads well in zh/en.
3. Version check scripts pass (check-release-version, release-notes, changelog check).
4. Tag and confirm the release workflow finishes and artifacts are published.
5. Post the headline (and recording if any).

Open questions

1. Who creates the tag: a maintainer by hand at first, or a scheduled workflow later?
2. Fixed time of day, and how to treat very large days (split into two tags?).
3. Do we keep a separate "stable" channel later, or is every tag stable?
4. What happens to Prepare the FlyBot v0.2.0 product release #152: close it in favour of the daily flow, or land it as the first tag?

Process

Workflow or script changes go through cloud OpenCode, review via Codex; bots do not hand-write code.