feat: add IaC partial ownership commands

[brody192]

Named IaC ownership can outlive its authoring file and block moving resources between partials or returning to whole-project management. Add railway config partials list, release, and transfer to manage that ownership without deleting resources, changing their configuration, or redeploying them.

Release and transfer support selected addresses or an entire source partial, preview every affected address, and send that exact selection with the existing Environment.configEtag. Reuse linked-environment resolution, token authentication, partial-name validation, confirmations, and JSON behavior. --dry-run and --base-config-etag support separate CI review and execution without introducing another saved-plan format. Update command help and the IaC guide with configuration and re-planning guidance.

Validation:

• cargo test --locked: 1,692 passed, six ignored, including seven ownership unit tests and ten CLI integration tests covering terminal confirmation/cancellation, human/JSON output, scoped project tokens, selection errors, stale snapshots, old-backend errors, file preservation, and invalidation of saved config plans.
• cargo fmt --all -- --check, cargo clippy --locked --all-targets --all-features, native cargo build --release --locked, and git diff --check passed. Clippy reports existing warnings. The Windows cross-build is left to CI.

Uses the ownership mutations added in https://github.com/railwayapp/mono/pull/40200. Backend rollout is tracked separately; unsupported servers return an API error without falling back to a resource apply. Companion documentation: railwayapp/docs#1365 (draft pending CLI release and backend availability).