feat: add manual trigger to WinGet publish workflow

Accepts a tag input (e.g. v1.0.0) for manual dispatch. Looks up
the release by tag instead of using the event payload, so it works
for both release events and manual triggers.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

fix: enforce strict word limit for highlight descriptions

Max 10-15 words per item. No multi-sentence explanations.
Skip summary paragraph for small releases.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

fix: improve release highlights change detection and formatting

- Treat commits as primary source, not just PRs
- Inspect significant commits with git show to understand scope
- Use PR author for attribution, fall back to commit author
- Add 🌐 Localization section for translation updates
- Add Full Changelog comparison link
- Keep descriptions concise (one sentence per item)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

fix: make highlights more concise, add changelog link, fix author att…

…ribution

- Keep descriptions to one sentence per item
- Use PR author (not commit author) for attribution
- Add Full Changelog comparison link at the end

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

feat: include author and PR references in release highlights

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

fix: use correct path for highlights in agent artifact

The agent artifact extracts to agent/release-highlights.md,
not at the root.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

fix: write highlights to /tmp/gh-aw/agent/ for artifact collection

Write highlights to /tmp/gh-aw/agent/release-highlights.md which is
automatically collected in the agent artifact. No safe outputs needed
for file storage — just shell write + noop. Release workflow downloads
the agent artifact to get the file.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

fix: simplify highlights output by writing file directly

Remove custom safe-output job entirely. Instead, the agent writes
highlights to /tmp/gh-aw/release-highlights.md via shell, which is
automatically collected in the agent artifact. The release workflow
downloads the agent artifact to get the file.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

fix: enforce single save_highlights call and improve output extraction

- Instruct agent to call save_highlights exactly once (system limit)
- Improve jq to find last item with highlights field across all items
- Prevents 'Too many items' errors from duplicate calls

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

fix: improve release highlights integration and error handling

Release workflow:
- Use timestamp and event-based API filtering to identify the
  dispatched highlights run, avoiding race conditions
- Replace verbose gh run watch with quiet polling loop
- Skip artifact download when highlights workflow fails
- Surface download errors as warnings instead of suppressing

Release highlights prompt:
- Compare against last published release, not previous tag
- Prioritize commits over PRs for change detection
- Try multiple jq paths when extracting agent output
- Stop agent immediately after saving highlights

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>