ci(publish): finalize Sentry release after publishing (#450)

## Summary

Add Sentry release finalization to the publish workflow. Currently,
sourcemaps are uploaded during CI builds but the release is never
finalized — meaning Sentry doesn't track commits, deploys, or release
health for published versions.

## Changes

**`.github/workflows/publish.yml`**

1. **New step: "Finalize Sentry release"** (after `craft publish`,
before issue close):
- `sentry-cli releases set-commits --auto` — associates commits since
the previous release tag
- `sentry-cli releases finalize` — marks the release as live with a
`dateReleased` timestamp
- `sentry-cli releases deploys new -e production` — creates a deploy
marker for release health

2. **Added `fetch-tags: true`** to the checkout step so `set-commits
--auto` can find the previous release tag boundary.

3. **Uses `continue-on-error: true`** since this is post-publish
telemetry — a Sentry API outage must not block the issue from being
closed or trigger false "publish failed" comments.

## What this does NOT change

- CI (`ci.yml`) — sourcemap upload stays where it is
- `.craft.yml` — no Craft config changes needed
- Build scripts — they continue to handle sourcemap upload with debug
IDs