fix: resolve ACP bridge interpreters from home env

[matt2e]

Summary:

• Resolve env-shebang ACP bridge launchers with the home/global PATH snapshot before startup.
• Keep the working-directory environment snapshot as the child process environment for local sessions.
• Add driver coverage for explicit interpreter launch and remote-session behavior.

Test Plan:

• crates-fmt, crates-lint, crates-test, differ-ci, staged-ci (during push).