feat: add GNU screen wrapping with process monitor

Add screen session management infrastructure:
- ScreenManager class to create, track, and kill GNU screen sessions
- Persistence of screen sessions to ~/.claudeman/screens.json
- Process stats collection (memory, CPU, child count)
- Reconciliation to detect dead/orphan screens

New API endpoints:
- GET /api/screens - list screens with stats
- DELETE /api/screens/:sessionId - kill screen
- POST /api/screens/reconcile - find dead screens
- POST /api/screens/stats/start|stop - control stats polling

New Process Monitor panel:
- Slide-up panel with real-time stats (2s updates)
- Shows memory, CPU, child processes per screen
- Kill button for each screen session
- Reconcile button to clean up dead screens

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

src/web/public/styles.css

@@ -1118,6 +1118,124 @@ kbd {
   background: var(--border-light);
 }
 
+/* Process Monitor Panel */
+.process-panel {
+  position: fixed;
+  bottom: var(--toolbar-height);
+  left: 0.5rem;
+  width: 400px;
+  max-width: calc(100vw - 1rem);
+  max-height: 50vh;
+  background: var(--bg-card);
+  border: 1px solid var(--border);
+  border-bottom: none;
+  border-radius: 8px 8px 0 0;
+  box-shadow: 0 -4px 20px rgba(0, 0, 0, 0.4);
+  z-index: 100;
+  transform: translateY(100%);
+  transition: transform 0.2s ease;
+  display: flex;
+  flex-direction: column;
+}
+
+.process-panel.open {
+  transform: translateY(0);
+}
+
+.process-panel-header {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: 0.6rem 1rem;
+  border-bottom: 1px solid var(--border);
+  font-size: 0.8rem;
+  font-weight: 500;
+  flex-shrink: 0;
+}
+
+.process-panel-actions {
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+}
+
+.process-panel-body {
+  flex: 1;
+  overflow-y: auto;
+  padding: 0.5rem;
+}
+
+.process-empty {
+  padding: 1rem;
+  text-align: center;
+  color: var(--text-muted);
+  font-size: 0.8rem;
+}
+
+.process-item {
+  display: flex;
+  align-items: center;
+  gap: 0.75rem;
+  padding: 0.6rem 0.75rem;
+  background: var(--bg-input);
+  border-radius: 4px;
+  margin-bottom: 0.5rem;
+}
+
+.process-item:hover {
+  background: var(--bg-hover);
+}
+
+.process-info {
+  flex: 1;
+  min-width: 0;
+}
+
+.process-name {
+  font-size: 0.8rem;
+  color: var(--text);
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+
+.process-meta {
+  display: flex;
+  gap: 0.75rem;
+  font-size: 0.7rem;
+  color: var(--text-muted);
+  margin-top: 0.2rem;
+}
+
+.process-stat {
+  display: flex;
+  align-items: center;
+  gap: 0.25rem;
+}
+
+.process-stat.memory { color: var(--accent-hover); }
+.process-stat.cpu { color: var(--green); }
+.process-stat.children { color: var(--yellow); }
+
+.process-actions {
+  display: flex;
+  gap: 0.25rem;
+}
+
+.process-mode {
+  font-size: 0.6rem;
+  padding: 2px 6px;
+  border-radius: 3px;
+  background: var(--bg-hover);
+  color: var(--text-muted);
+  text-transform: uppercase;
+}
+
+.process-mode.shell {
+  background: rgba(234, 179, 8, 0.2);
+  color: var(--yellow);
+}
+
 /* Responsive */
 @media (max-width: 600px) {
   .header-brand {