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/help.html

@@ -45,6 +45,27 @@
       <li><strong>Ahead / behind</strong> — commits your branch leads or trails its upstream by.</li>
     </ul>
 
+    <h2>Right-click commands</h2>
+    <p>
+      Right-click any repository for a menu of plain-language commands — no git
+      knowledge needed:
+    </p>
+    <ul>
+      <li><strong>Get latest</strong> — pull the newest changes.</li>
+      <li><strong>Publish</strong> — push your commits.</li>
+      <li><strong>Check for updates</strong> — fetch without changing your files.</li>
+      <li><strong>Save my work…</strong> — commit everything (asks for a message).</li>
+      <li><strong>Set as active project</strong> / <strong>Ask Claude to switch here</strong>.</li>
+      <li><strong>Copy path</strong>.</li>
+      <li><strong>Discard all changes…</strong> — throw away uncommitted edits
+        (asks you to confirm; can't be undone).</li>
+    </ul>
+    <p>
+      What each command did shows up in the activity panel. (Get latest / Publish /
+      Check for updates need your server to have git credentials; until then they'll
+      report a sign-in error.)
+    </p>
+
     <h2>Repository details</h2>
     <p>
       Click any repository in the list to open its details on the right: its