Type UAV test infrastructure and peer contracts

[ethayu]

Fixes #242.
Fixes #244.
Fixes #246.
Fixes #250.
Part of #201.

Summary

• Type ROS/import stubs and guarded dynamic launch-module loading in UAV tests.
• Cast test-only ModeManager fakes where tests bypass ROS constructors.
• Type OpenCV/NumPy payload DLZ fixtures at cv2 stub boundaries.
• Type UAV peer contract and live reconnect test helpers.
• Folded Type UAV peer contract tests #247 into this PR as a separate commit.

Verification

• Constituent focused Pyright, compile, ruff, and UAV pytest checks from Type UAV test infrastructure and peer contracts #243 and Type UAV peer contract tests #247 passed when created.
• Dynamic peer reconnect check after condensation: 1 passed in 17.75s.

Full touched-file pytest including all of test_schema_validation.py still fails on an existing checked-in fleet fixture referencing missing payload_full_run.yaml.