Support PermissionRequest hook deny interrupts

[abhinav-oai]

Summary

• allow PermissionRequest hooks to return decision.interrupt: true alongside behavior: "deny"
• route interrupting denies through the same turn-abort path used by an Esc interrupt
• add integration coverage for shell, exec_command, network approval, and a verified subagent smoke path

Why

PermissionRequest hooks could deny a request, but they could not force the active agent loop to stop immediately. That made policy-driven hard stops behave differently from a user interrupt even when the hook author wanted the turn to terminate.

Impact

• hook authors can now short-circuit a denied request cleanly by setting interrupt: true
• denied requests without interrupt: true keep the existing rejection behavior
• interrupt semantics are preserved across the command-execution and approval paths that can hit PermissionRequest hooks

Validation

• cargo test -p codex-hooks permission_request_
• cargo test -p codex-core permission_request_hook_
• cargo run -p codex-hooks --bin write_hooks_schema_fixtures
• just fix -p codex-hooks
• just fix -p codex-core
• just fmt
• interactive TUI smoke test confirming an interrupting deny from a spawned subagent request

Stack

• base branch: codex/permission-request-hooks-base