feat: Plugin Builder, Brain Inbox, and OpenAI TTS (v0.24.12)

[jpelaez-23blocks]

Summary

• Plugin Builder page — Visual skill composition interface for building Claude Code plugins with repo scanning, skill picking, and build/push workflow
• Brain inbox system — JSONL signal queue enabling cerebellum and subconscious to surface signals (memories, warnings, notifications) to the cortex via the idle_prompt hook
• OpenAI TTS wiring — Provider toggle and API key input in companion UI, unlocking the mid-tier voice ($15/M chars vs ElevenLabs $206/M)
• Message event detection — Cerebellum now classifies AMP notifications in terminal output as message events with 0ms cooldown for immediate speech
• Hook optimization — Single agent lookup shared across all check functions, combined notification delivery to prevent race conditions

Test plan

• yarn test — 486 tests pass
• yarn build — production build succeeds
• Open /companion, select OpenAI provider, enter API key, verify speech plays
• Send AMP message to agent, verify cerebellum speaks notification
• Trigger memory indexing, check ~/.aimaestro/agents/{id}/brain/cortex-inbox.jsonl for signals
• Open /plugin-builder, scan a repo, compose a plugin, verify build output
• Wait for idle_prompt hook, verify combined notification delivery

🤖 Generated with Claude Code