Wire heartbeat module to telemetry endpoint in daemon event loop

[Brad-Edwards]

Problem

daemon/heartbeat.c implements frame-count anomaly detection (freeze/rewind) and timeout tracking. It has 10 unit tests, all passing. But it's never called from the daemon's event loop or connected to the Lambda telemetry API (platform/api/handler.py has POST /heartbeat ready).

The heartbeat tracker is dead code in production — fully implemented, tested, and unused.

What exists

• daemon/heartbeat.{h,c} — owl_hb_register(), owl_hb_process(), owl_hb_check_timeout(), anomaly detection
• platform/api/handler.py — POST /heartbeat endpoint, returns action (continue/kill/pause), DynamoDB storage
• daemon/main.c — no heartbeat initialization, no periodic heartbeat send, no telemetry HTTP client

What's missing

1. Heartbeat send loop — periodic POST to telemetry API with frame count, state hash, timestamp
2. HTTP client in daemon — libcurl is already in LDFLAGS (-lcurl) but unused
3. API key retrieval — SSM parameter store has the key; daemon needs to read it or accept via CLI/env
4. Response handling — telemetry API can return kill/pause actions; daemon should honor them

Acceptance

• Daemon sends heartbeats to configured telemetry endpoint every N seconds
• Telemetry API receives and stores heartbeats
• Frame freeze/rewind anomalies detected and reported
• Timeout (missed heartbeats) generates OWL_EVENT_HEARTBEAT_MISSED