Port Twix map panel to ros-z topics

[schmidma]

Depends on #2637; GitHub diff includes earlier commits until that base merges.

Summary

• Register Map as a supported retained-state ros-z panel.
• Render active map layers from typed ros-z-debug retained handles with explicit retention policies.
• Use native ground_to_field type, transient-local field dimensions, and suppress stale retained map data on diagnostics.

Test Plan

• cargo nextest run -p twix
• cargo check -p twix
• cargo clippy -p twix --all-targets --locked -- -D warnings
• cargo nextest run -p ros-z-debug
• git diff --check