[Bug] Update notice shows raw release download link

[Astro-Han]

What happened?

After updating to PawWork v0.2.5, the app shows the post-update notice modal with a raw Markdown download link as the main content: [macOS Apple Silicon](https://github.com/Astro-Han/pawwork/releases/download/v0.2.5/pawwork-mac-arm64.dmg). This makes the update notice feel like a technical artifact rather than a useful confirmation of what changed.

Steps to reproduce

1. Install or update from a previous PawWork version to v0.2.5.
2. Launch PawWork after the update.
3. Wait for the update notice modal to appear.
4. See the raw release download link in the modal body.

What did you expect to happen?

The post-update notice should lightly confirm that PawWork was updated and summarize the user-visible value of the release. It should not display download links, verification details, PR numbers, or maintenance-only release notes as the primary product message.

PawWork version

v0.2.5

OS version

macOS, observed on Apple Silicon.

Can you reproduce it again?

Only once so far through the shipped update path, but the cause is reproducible from the current parser and the live v0.2.5 GitHub Release body. The app skips headings and uses the first non-heading line, while the release body starts with a Downloads section.

Extra context

Current direction: keep this as a lightweight one-time update reminder, but make the content product-controlled. A likely fix is to add a dedicated app-facing section to the GitHub Release, for example ## App Update Notice, and have the app read only that section. If the section is missing, the app should not guess from the general release body. This should be handled together with the next release flow and release note template update, not as an isolated UI tweak.

[Astro-Han]

Related context for later triage:

This showed up after the v0.2.5 release because the app update notice parser reads the live GitHub Release body and currently picks the first non-heading line. The v0.2.5 release body starts with a Downloads section, so the modal surfaced the first download link instead of the user-facing highlights.

Release content that fed this notice came from v0.2.5, especially PRs included in the release notes: #89 for macOS Intel and Windows release targets, #90 for Review Git changes UI polish, #101 for sync store availability during route changes, #105 for macOS lifecycle behavior, #109 and #114 for stale assistant message and running-state fixes, and #99 for removing Traditional Chinese product support. Maintenance-only items in the same release included #102, #93, #97, #108, and #118.

Adjacent release-flow issues are #86 for macOS Intel artifacts and #87 for the Windows release path. #84 is also related context because it covered desktop menu and updater UX cleanup.

Product direction from triage: keep a lightweight one-time update reminder, but make its content product-controlled. The likely follow-up is to add a dedicated app-facing section to the GitHub Release, for example ## App Update Notice, and make the app read only that section. If the section is missing, the app should avoid guessing from Downloads, Verification, PR lists, or maintenance sections.