feat: use Task tool description for subagent window titles + auto-minimize completed

- Extract short description from TaskTracker (params.description) for subagent windows
- Correlate subagents with sessions by working directory and timing
- Auto-minimize subagent windows when agents complete
- Persist minimized/open window states to server for cross-browser sync
- Restore window states on reconnection/page reload
- New API: GET/PUT /api/subagent-window-states
- State file: ~/.claudeman/subagent-window-states.json

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/web/public/styles.css

@@ -2103,6 +2103,21 @@ body {
   color: var(--text-dim);
 }
 
+.run-summary-footer {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  margin-top: 1rem;
+  padding-top: 0.75rem;
+  border-top: 1px solid var(--border);
+}
+
+.run-summary-actions {
+  display: flex;
+  align-items: center;
+  gap: 0.75rem;
+}
+
 .modal-footer-actions {
   display: flex;
   align-items: center;