Bound camera RPC waits and feed shutdown

[walker2398]

Summary

• add configurable native gRPC deadlines to single-image capture and streaming-status queries
• explicitly cancel the underlying camera-feed iterator during shutdown
• bound feed shutdown and its remote streaming-status checks

Root cause

Camera RPCs previously had no deadlines. close_camera_feed() attempted to enforce a ten-second limit with a polling loop, but each image_streaming_enabled() call used an unbounded future.result(). A delayed robot or network could therefore block shutdown indefinitely. Cancelling the task also did not explicitly cancel the wrapped gRPC iterator.

This change intentionally keeps the existing gRPC transport and public behavior. It does not add an HTTP fallback or another camera workflow.

Validation

• Python 3.11 and 3.12: anki_vector/camera.py compiles successfully
• git diff --check
• Vector firmware 2.0.1.6076ep: capture returned 640x360 in 0.797 seconds; CameraFeed delivered a frame; close completed in 0.409 seconds; IsImageStreamingEnabled returned false afterward