Pylance: type UAV CV array helpers

[ethayu]

Problem

The integrated workspace Pyright pass reports CV helper diagnostics around OpenCV array types and real nullable/unbound paths:

• contour arrays passed through OpenCV helpers without normalization
• HSV tuple bounds passed where OpenCV stubs expect array-like values
• connectedComponentsWithStats called with positional connectivity that Pyright reads as labels
• debug visualization images possibly unbound
• debug-only image reads/decode paths not guarded before processing

Acceptance

• The focused Pyright slice for uav/cv/tracking.py, threshold.py, confidence.py, and dlz_color_regions.py is clean.
• The touched files pass python3 -m compileall, ruff check, and ruff format --check.
• The existing DLZ CV test passes.

Parent tracker: #201

[ethayu]

Resolved by consolidated PR #237 and tracked under parent #201. Closing this leaf issue after issue/PR condensation.