feat: unify agent actions and give Codex live control

[pathscale]

Summary

• replace legacy task JSONL, checkbox, and prose PR mutation paths with one declared Prompt Syntax surface
• parse streamed directives safely across Markdown fences and reject disguised bidi controls
• upgrade agent-abstraction to 0.4.5 so Codex projects use app-server with live text, approvals, writable roots, sessions, and mid-turn steering
• keep Ask available for Codex and let Auto request access when a project root was not declared
• bump the workspace to 0.1.56 in an isolated commit

Verification

• cargo test --workspace
• cargo clippy --workspace --all-targets -- -D warnings
• cargo check --workspace after the version bump
• bun run typecheck
• bun run test:run (263 tests)
• bun run build
• bun run lint