[codex] fix: remove shadowed _generated_sibling_path overload breaking smoke test

[markoblogo]

Problem

The feat(status) commit (36d0b93) introduced a new _generated_sibling_path(path, generated_suffix) function at the bottom of actions.py for the new status command. However, a legacy _generated_sibling_path(path) definition (single argument, no suffix) already existed earlier in the same file.

Python resolved this to the last definition, so when _handle_file called _generated_sibling_path(path) (single-arg form) it hit the new two-arg signature — causing:

FAIL test3_no_markers_creates_generated_files: _generated_sibling_path() missing 1 required positional argument: 'generated_suffix'

Both Python 3.11 and 3.12 CI jobs failed on test3_no_markers_creates_generated_files.

Root cause

Duplicate function definition: the old one-arg version at line 245 was silently shadowed by the new two-arg version added for the status command.

Fix

• Removed the now-dead one-arg _generated_sibling_path definition (lines 245–250).
• Updated the single call site in _handle_file (line 208) to pass ".generated" as the suffix, matching the previous default behaviour exactly (AGENTS.md → AGENTS.generated.md, RUNBOOK.md → RUNBOOK.generated.md).

Verification

All three smoke tests pass locally:

PASS test1_init_creates_files_and_config
PASS test2_update_preserves_outside_markers
PASS test3_no_markers_creates_generated_files

Run: python -m agentsgen._smoke