Add keyboard shortcut 'W' for creating new agent session

- Added newSession shortcut to ACTION_SHORTCUTS in use-keyboard-shortcuts.ts
- Updated SessionManager to expose quick create function via ref
- Updated AgentView to register the shortcut and trigger new session creation
- Display shortcut key indicator (W) on the New session button
- Updated feature_list.json to mark feature as verified

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

.automaker/feature_list.json

@@ -54,6 +54,6 @@
     "category": "Agent Runner",
     "description": "Can you please add a shortcut for starting a new session?",
     "steps": [],
-    "status": "backlog"
+    "status": "verified"
   }
-]
+]