Slice 6: right-click command menu + git write actions

git boundary: Pull/Push/Commit/DiscardAll (discard is 1.4-destructive). Scanner.RefreshRepo re-scans one repo after a mutation. Service GitFetch/GitPull/GitPush/GitCommit/GitDiscard record a git-* activity event and refresh on success; service.New takes a refresh hook. HTTP POST /api/repo/git. New <repo-menu> overlay with plain-language commands (Get latest/Publish/Check for updates/Save my work/Set active/Ask Claude to switch/Copy path/Discard all changes), summoned by repo-list's repo:contextmenu. Added service test for commit/discard on a temp repo. Verified the menu live for safe commands.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

web/templates/index.html

@@ -12,6 +12,7 @@
   <script type="module" src="/components/activity-feed/activity-feed.js"></script>
   <script type="module" src="/components/handoff-bar/handoff-bar.js"></script>
   <script type="module" src="/components/pr-list/pr-list.js"></script>
+  <script type="module" src="/components/repo-menu/repo-menu.js"></script>
   <style>
     header {
       display: flex;
@@ -53,5 +54,6 @@
     </div>
     <activity-feed></activity-feed>
   </main>
+  <repo-menu></repo-menu>
 </body>
 </html>