fix(agents): Leave changes made before a local checkout task out of its changes (#123)

* fix(agents): Leave changes made before a local checkout task out of its changes

A task in the project's own checkout listed every uncommitted and untracked
file as its own. The files already changed when the task starts are now
recorded with their size and modification time, and drop out of the task's
changes until they are edited again.

* feat(agents): Show the current branch for a local checkout task

src/features/agents/Home.module.css

@@ -34,6 +34,15 @@
   padding: 0 2px;
   font-size: var(--fs-small);
 }
+/* The current branch, read-only: same height and colour as the pickers beside it. */
+.branch {
+  display: inline-flex;
+  align-items: center;
+  gap: 4px;
+  height: var(--h-control);
+  padding: 0 6px;
+  color: var(--fg-secondary);
+}
 .project {
   margin-right: 6px;
   color: var(--fg-muted);