perf: reduce mobile terminal latency

[AnthonyAlcaraz]

Summary

This PR improves responsiveness when using the Happy app on mobile networks with variable latency.

Changes:

• Reduce socket.io reconnection delay from 1000ms to 500ms for faster recovery after disconnections
• Reduce max reconnection delay from 5000ms to 3000ms
• Reduce activity update debounce from 2000ms to 500ms for faster terminal feedback
• Add 15-second timeout wrapper for voice session operations to prevent hanging on poor networks

Root Cause Analysis

The mobile terminal execution was slow due to:

1. Long reconnection delays - Socket.io defaults were tuned for desktop reliability, not mobile responsiveness
2. Activity updates throttled to 2 seconds - The ActivityUpdateAccumulator debounced ephemeral updates for 2 seconds, creating noticeable lag for terminal feedback
3. No timeout on session start - startRealtimeSession() could hang indefinitely on poor networks

Test Plan

• Test on mobile device with good WiFi - should feel snappier
• Test on cellular network - reconnections should recover faster
• Test with poor network conditions - session start should timeout gracefully instead of hanging
• Verify typecheck passes (yarn typecheck)

Impact

These are safe, conservative changes:

• Reconnection delays are still reasonable (500ms-3000ms)
• Activity debounce of 500ms is still enough to batch rapid updates
• 15-second timeout is generous while preventing indefinite hangs

---

Generated with Claude Code