Usage tracking, model-tier feedback loops, and agent-coordination signals

Notes & tips

• Depend on the documented public surface. The supported API is the classes exported from attune.telemetry; the per-module internals (file layout, buffering) are implementation details.
• Use the singleton for reads. UsageTracker.get_instance() reads the same store workflows write to; constructing a fresh tracker with a different telemetry_dir reads a different store.
• flush() before reading freshly written calls. Writes are buffered.
• Coordination needs Redis. Gate EventStreamer / HeartbeatCoordinator use behind TelemetryFeatures.