fix(ruby): honor localfs for cross-container attach

[debugmcpdev]

Description

Fixes #499.

• honors an explicitly supplied boolean adapterConfig.localfs for Ruby attach
• falls back to host-based inference only when localfs is omitted or invalid
• preserves localfsMap passthrough
• extends the Docker attach smoke test to mount source at the same target/client path, bind and hit a line breakpoint, inspect locals, detach, and confirm the target survives
• corrects the Ruby guide to place localfs/localfsMap inside adapterConfig and documents rdbg's Windows drive-colon mapping limitation

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• Documentation update
• Test improvement

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented hard-to-understand behavior
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove the fix is effective
• New and existing unit tests pass locally with my changes
• No downstream publication is required

Testing

pnpm run build
pnpm run test:unit                    # 230 files, 4,277 tests
pnpm run test:integration             # 8 passed / 2 skipped; 23 passed / 5 skipped
pnpm run lint
pnpm run check:personal-paths
git diff --check
vitest --project e2e tests/e2e/docker/docker-smoke-ruby-attach.test.ts
                                        # 2 tests passed against real sibling containers

Source dev-proxy dogfooding also stopped inside the compiled transform, inspected locals, and evaluated explicit remote true and loopback false results. A live rdbg attach then hit long_running.rb, returned counter, message, and squared, evaluated an expression, and survived detach.

Test configuration: Windows x64, Docker Desktop Linux containers, Ruby 3.4/rdbg 1.11.0, Node.js 24.14.1, pnpm 10.33.0

Related Issues

• Closes ruby attach across a container boundary can bind no breakpoints: localfs is silently overridden, localfsMap is inert #499

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Reviewer: @debugmcp

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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