Add interactive Codex app-server transport

[pathscale]

Summary

• route interactive Codex runs through app-server for live turn steering and approvals
• stream assistant deltas, tool events, session IDs, context usage, and explicit workspace roots
• add provider-neutral additional working roots for Claude and Codex
• release as 0.4.5 in an isolated commit

Verification

• cargo test --lib: 190 passed
• relevant non-quota live tests: passed
• cargo clippy --all-targets -- -D warnings: passed
• cargo doc --no-deps with warnings denied: passed
• real Codex live steer test: passed
• real Codex approval denial test: passed