Improve Metro ride safety and harden Regions runtime

[angushushu]

What changed

• Metro: adds in-transit distance feedback, optional cruise control, passenger exit locking, safer plugin-driven minecart ejection, Bedrock arrival synchronization, GUI item-leak cleanup, configuration updates, and regression coverage.
• Regions: completes runtime trigger coverage, strengthens capability validation and effect escrow behavior, improves region detection caching, localizes player-facing messages, and splits the oversized GUI coordinator into focused menu components.
• Updates Regions architecture, regression baseline, plan, changelog, and contributor invariants to match the implementation.

Why

These changes improve Metro passenger safety and travel feedback while closing Regions runtime and validation gaps and making its GUI implementation easier to maintain and review.

Validation

• ./gradlew :Metro:test :Metro:build --no-daemon --rerun-tasks — passed; 600 tests, 0 failures.
• ./gradlew :Regions:test :Regions:build :Regions:shadowJar --no-daemon --rerun-tasks — passed; 71 tests, 0 failures.
• Confirmed non-plain release JARs for both modules were produced.