Clean up Duplicate Surfacing comment noise (#6412) (#6414)

## 📖 Description

Reduces noise in the **Duplicate Surfacing** workflow's comment, per
maintainer feedback in #6412.

Three changes to `.github/workflows/duplicate-surfacing.md` (and its
regenerated `.lock.yml`):

1. **Header** — drop the `(surfaced automatically for maintainer review
— this issue has **not** been closed)` parenthetical. The comment is now
just `**Possible duplicates:**`.
2. **Guidance** — reword from maintainer-facing to
**contributor-facing**: thank the submitter, ask them to review the
candidates, and — if one matches — to 👍 that issue and close this one as
a duplicate. Keeps the note that older/curated issues are preferred as
canonical. Removes the `Duplicate of #` instruction (maintainers
already know the trigger, and this avoids surfacing the auto-close
phrase in the comment body).
3. **Footer** — replace the auto-generated `> Generated by 🔁 Duplicate
Surfacing … · sonnet46 · NN AIC · …` footer with a single consolidated
line via `safe-outputs.messages.footer`:

   ```
Template: msftbot/duplicate/surfaced by [Duplicate
Surfacing]()
   ```

This keeps the `Template:` tag (for email-filter rules) and a link back
to the workflow run, while dropping the token/cost metadata noise.
Rendered as an H6 heading (`######`) to visually de-emphasize it. The
invisible `` dedup markers are unaffected (they're added
separately and are required so the workflow doesn't re-comment).

### Rendered comment (after)

> **Possible duplicate(s):**
>
> Thank you for submitting this issue.
>
> The issue(s) below may already track your request or bug. Please take
a look — if one of them matches, give that issue a 👍 and close this one
as a duplicate. Older or curated issues are preferred as the canonical
one to follow.
>
> - #472 — Requests the same feature: …
> - #1103 — Same underlying bug: …
>
> ###### Template: msftbot/duplicate/surfaced by [Duplicate
Surfacing](https://github.com/microsoft/winget-cli/actions/runs/…)

## 🔗 References

Resolves #6412

## 🔍 Validation

- `gh aw compile duplicate-surfacing` → 0 errors, 0 warnings.
- Verified the footer template is embedded in the generated lock as
`GH_AW_SAFE_OUTPUT_MESSAGES` and that `GH_AW_RUN_URL` /
`GH_AW_WORKFLOW_NAME` are wired in to render the `{run_url}` /
`{workflow_name}` placeholders.

## ✅ Checklist

- [x] Signed the [Contributor License
Agreement](https://cla.opensource.microsoft.com)
- [x] Linked to an issue
- [ ] Updated [Release Notes](../doc/ReleaseNotes.md) (if applicable)
- [ ] Updated documentation (if applicable)
- [ ] Updated [Copilot instructions](.github/copilot-instructions.md)
(if build, architecture, or conventions changed)

## 📋 Issue Type

- [x] Task

---
Authored with GitHub Copilot assistance.

Co-authored-by: Demitrius Nelon 
Copilot-Session: 3701d64a-96ba-42f1-be59-b4e7d2a2820a

Author: denelon

.github/workflows/duplicate-surfacing.lock.yml

@@ -18,6 +18,8 @@ tools:
       - "${{ github.repository }}"
     min-integrity: none
 safe-outputs:
+  messages:
+    footer: "###### Template: msftbot/duplicate/surfaced by [{workflow_name}]({run_url})"
   report-failure-as-issue: false
   noop:
     report-as-issue: false
@@ -85,17 +87,17 @@ If you have at least one likely-duplicate candidate:
 1. Apply the `Possible-Duplicate` label with `add_labels`.
 2. Post exactly one comment with `add_comment` in this shape:
 
-   > **Possible duplicates** (surfaced automatically for maintainer review — this
-   > issue has **not** been closed):
+   > **Possible duplicate(s):**
    >
-   > - #<number> — <one-line why it matches>
-   > - #<number> — <one-line why it matches>
+   > Thank you for submitting this issue.
    >
-   > Maintainers: if one of these is the canonical issue, comment
-   > `Duplicate of #` to consolidate. Earlier/curated issues are
-   > preferred as canonical.
+   > The issue(s) below may already track your request or bug. Please take a
+   > look — if one of them matches, give that issue a 👍 and close this one as a
+   > duplicate. Older or curated issues are preferred as the canonical one to
+   > follow.
    >
-   > Template: msftbot/duplicate/surfaced
+   > - #<number> — <one-line why it matches>
+   > - #<number> — <one-line why it matches>
 
 ### Hard rules