fix(computer_use): route CUA capture through get_window_state

[jeeves-assistant]

Summary

• Routes CUA vision/SOM/AX captures through get_window_state instead of the stale standalone screenshot MCP tool.
• Passes capture_mode="vision" / "som" / "ax" so cua-driver 0.5.x returns the expected payload shape.
• Preserves AX no-image behavior and prefers structuredContent screenshot dimensions when cua-driver provides them.
• Adds the Jeeves Assistant author-map entry required by CI attribution checks.

Verification

• python -m pytest tests/tools/test_cua_backend_capture.py tests/tools/test_computer_use.py tests/tools/test_computer_use_capture_routing.py tests/tools/test_computer_use_vision_routing.py -q -o 'addopts=' → 128 passed, 1 warning
• python -m py_compile scripts/release.py tools/computer_use/cua_backend.py tests/tools/test_cua_backend_capture.py
• git diff --check

Related: #39242. This is intentionally the narrow reversible seam described in the field notes; it mirrors the existing upstream fix direction without adding new runtime surface.

[alt-glitch]

Duplicate of #39262 — same fix for #39242: route CUA vision/SOM/AX captures through get_window_state(capture_mode=...) instead of the non-existent standalone screenshot MCP tool. #39262 is the earliest open PR with this exact mechanism. See also the related cluster #39342, #42158, #44715.

[jeeves-assistant]

Closing as a duplicate. I opened this before properly checking the already-open CUA capture PRs; #39262 and #39342 already cover the same get_window_state / capture_mode direction for #39242. I will keep any local runtime hotfix separate and use the existing upstream PRs as the artifact of record.