fix: remove legacy C impl, add -v to fallback docker rm, fix tests (#754)

- Remove one-shot-token.c (legacy C impl kept "for reference" after Rust
  port). The Rust implementation in src/lib.rs is the sole implementation.
- Add -v flag to fallback `docker rm -f` in stopContainers to clean
  orphaned volumes, matching the `docker compose down -v` normal path.
- Fix pre-existing test failures: update stdio expectations to match the
  PR's ['ignore', 'ignore', 'inherit'] pattern, create docker-compose.yml
  in stopContainers test so the normal path is exercised, and add a new
  test for the fallback (missing compose file) path.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Mossaka

containers/agent/one-shot-token/README.md

@@ -308,5 +308,4 @@ This library is one layer in AWF's security model:
 - `src/lib.rs` - Library source code (Rust)
 - `Cargo.toml` - Rust package configuration
 - `build.sh` - Local build script
-- `one-shot-token.c` - Legacy C implementation (for reference)
 - `README.md` - This documentation