feat: Python telemetry client SDK v0.1.0

Standalone Python package (mosaicstack-telemetry) for reporting
task-completion telemetry and querying predictions from the Mosaic
Stack Telemetry server.

- Sync/async TelemetryClient with context manager support
- Thread-safe EventQueue with bounded deque
- BatchSubmitter with httpx, exponential backoff, Retry-After
- PredictionCache with TTL
- EventBuilder convenience class
- All types standalone (no server dependency)
- 55 tests, 90% coverage, mypy strict clean

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/conftest.py

@@ -177,7 +177,6 @@ def make_batch_response_json(events: list[TaskCompletionEvent]) -> dict:
         "accepted": len(events),
         "rejected": 0,
         "results": [
-            {"event_id": str(e.event_id), "status": "accepted", "error": None}
-            for e in events
+            {"event_id": str(e.event_id), "status": "accepted", "error": None} for e in events
         ],
     }