chore: replace team CODEOWNERS with external PR review workflow (#10104)

## Summary

Remove team assignments from CODEOWNERS to reduce notification noise for
internal PRs. Add a workflow that requests team review only when
external contributors open PRs.

## Changes

- **What**: Strip `@Comfy-org/comfy_frontend_devs` and
`@Comfy-Org/comfy_maintainer` from all CODEOWNERS entries (keep
individual user assignments). Add `pr-request-team-review.yaml` workflow
that uses `pull_request_target` to request team review for
non-collaborator PRs.
- **Dependencies**: None

## Review Focus

- The workflow uses `pull_request_target` but does not check out or
execute any untrusted code — it only runs `gh pr edit --add-reviewer`.
- The `author_association` check excludes OWNER, MEMBER, and
COLLABORATOR — internal PRs will not trigger team review requests.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-10104-chore-replace-team-CODEOWNERS-with-external-PR-review-workflow-3256d73d3650813b887ac16b5e97b4c4)
by [Unito](https://www.unito.io)

.github/workflows/pr-request-team-review.yaml

@@ -0,0 +1,24 @@
+# Request team review for PRs from external contributors.
+name: PR:Request Team Review
+
+on:
+  pull_request_target:
+    types: [opened, reopened]
+
+permissions:
+  pull-requests: write
+
+jobs:
+  request-review:
+    if: >-
+      !contains(fromJson('["OWNER","MEMBER","COLLABORATOR"]'),
+                github.event.pull_request.author_association)
+    runs-on: ubuntu-latest
+    steps:
+      - name: Request team review
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          gh pr edit ${{ github.event.pull_request.number }} \
+            --repo ${{ github.repository }} \
+            --add-reviewer Comfy-org/comfy_frontend_devs