feat(marks)!: v0.2.0 — marks replaces asks, and the CLI surface moves with it

The release that closes U2. Consumers have to adapt, which is what makes this a
minor rather than a patch: three things a scripted session can notice.

  * `booth asks <name>` now emits JSON, not the old aligned human table.
    Anything parsing those columns breaks. `booth marks <name>` is the name to
    use; `asks` survives as a deprecated alias for the muscle memory.
  * Polling `http://…/b/<n>/<stem>.answer.json` will 404 forever. There is no
    per-question answer sidecar any more. `GET /b/<n>/marks.json` replaces it and
    answers for the whole booth in one request — including an `open` list.
  * `#ask-<stem>` page anchors are now `#mark-<id>`, and `/b/<n>/asks` 308s to
    `/b/<n>/marks`.

What a session GAINS: the operator can now attach a note to any item or to the
booth, and flag individual items — both readable with `booth marks`. Selecting
winners out of a set used to be a chat message.

Nothing a session already wrote is lost. Legacy `*.ask.json` / `*.answer.json`
sidecars are imported by `booth marks-import <name>`, idempotently, and are
never deleted.

No lockfile step: this repo tracks none (uv.lock is gitignored, 790d5ba).

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "booth"
-version = "0.1.15"
+version = "0.2.0"
 description = "The Booth — a dead-simple standing web server that scans a data dir of drop-folders and renders each as an ephemeral media 'booth' (image/webm/audio auto-gallery, or a folder's own index.html verbatim). Also accepts browser/curl uploads for pickup under a human-readable id. 24h TTL, then the folder is wiped. Fleet tool for CC sessions to surface A/B and smoke results to the operator."
 requires-python = ">=3.11"
 dependencies = [