feat: add task management CLI and improve activity curation

- Add task store with dependency tracking and CLI (packages/server/src/tasks/)
- Extract principal param logic to shared util for server/app reuse
- Improve activity curator: collapse timeline, dedupe tool calls, simpler output
- Add MessageInput ref for focus control after agent cancel
- Include recent activity in wait timeout messages

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.tasks/2769910f.md

@@ -0,0 +1,15 @@
+---
+id: 2769910f
+title: Pick first random number
+status: done
+deps: []
+created: 2026-01-07T16:32:56.827Z
+---
+
+Pick a random number between 1-100. Record it in your notes as 'Number: X'. This is the starting value.
+
+## Notes
+
+**2026-01-07T16:33:43.884Z**
+
+Number: 47