M1-01: Move Gemini API key from URL query param to x-goog-api-key header,
preventing key leakage in logs/proxy/telemetry (matches Anthropic/OpenAI pattern)
M1-03/M1-04: Replace Mutex .unwrap() with .unwrap_or_else(|e| e.into_inner())
in MemoryMiddleware and LoopGuardMiddleware — recovers from poison
instead of panicking async runtime
M2-08: Add input validation to agent_create — reject empty names,
out-of-range temperature (0-2), and zero max_tokens
M11-06: Replace Date.now() message ID with crypto.randomUUID()
to prevent collisions in classroom chat