Improve task timeout and wire validation

[vikranthreddimasu]

Summary

• Await TaskDispatcher.map() results concurrently so per-task wait timeout does not multiply by input size.
• Validate TaskFuture.result() timeout values before creating wait coroutines.
• Reject malformed task result error payloads and task kwargs with invalid wire keys.

Security changes

• Tightened task wire validation for malformed RESULT error fields and TASK kwargs keys.
• Normalized msgpack strict-map-key decode failures into labeled validation errors.

Usability changes

• Invalid client wait timeouts now raise a clear ValueError instead of leaking lower-level asyncio behavior.
• Batch map failures no longer wait sequentially across all pending futures.

Tests/checks run

• python -m pytest tests/test_compute/test_dispatch.py tests/test_compute/test_models.py -q
• python -m pytest tests/test_compute/ -q
• make lint
• make test (1015 passed, 2 warnings)
• GitHub Actions test matrix: 11/11 passed
• git diff --check master...HEAD
• Diff-only secret scan with rg

Commits

• 3971f23 Fix task map timeout semantics
• 69e2d3d Validate task result error payloads
• c29fc7b Validate task kwargs on the wire

Risks / manual review notes

• Moderate behavior tightening: malformed task wire payloads fail earlier and invalid kwargs keys are rejected before execution.
• Does not touch authentication, credential handling, destructive actions, or deployment secrets.

Merge status

• Merged into master after local checks, diff-only secret scan, clean mergeability, and 11/11 GitHub checks passed.