Remove auto-assign from catalog submission workflow (#4054)

Catalog submission issues no longer auto-assign mnriem. The workflow now
only posts the team notification comment (cc @github/spec-kit-maintainers),
since GitHub issues cannot be assigned to a team. Renamed the workflow and
job to reflect its notification-only purpose.

Assisted-by: GitHub Copilot (model: Claude Opus 4.8, supervised)

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 63ae7e23-13e3-4a83-96b3-1178422aaa6e

Author: mnriem

.github/workflows/catalog-assign.yml

@@ -1,11 +1,11 @@
-name: "Catalog: Auto-assign submission"
+name: "Catalog: Notify submission"
 
 on:
   issues:
     types: [opened, labeled]
 
 jobs:
-  assign:
+  notify:
     if: >
       (github.event.action == 'opened' && (
         contains(github.event.issue.labels.*.name, 'extension-submission') ||
@@ -24,24 +24,8 @@ jobs:
       - uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9
         with:
           script: |
-            const issue = context.payload.issue;
-            const assigned = (issue.assignees || []).map(a => a.login);
             const marker = '<!-- catalog-assign-bot -->';
 
-            // Assign mnriem if not already assigned
-            if (!assigned.includes('mnriem')) {
-              try {
-                await github.rest.issues.addAssignees({
-                  owner: context.repo.owner,
-                  repo: context.repo.repo,
-                  issue_number: context.issue.number,
-                  assignees: ['mnriem'],
-                });
-              } catch (e) {
-                console.log(`Warning: could not assign mnriem: ${e.message}`);
-              }
-            }
-
             // Post team notification if not already posted
             const comments = await github.paginate(
               github.rest.issues.listComments,