AI-2146: fix stale notes.md and silent permission errors in init_task_record.py

[RachelXiaolan]

Mirrored from Linear AI-2146 (parent: AI-2145 — "Bug hunter 自动提交 PR 闭环演示").

Summary

Fix scripts/init_task_record.py so it can no longer silently leave a task folder with mismatched task.json / notes.md, and so it stops crashing with a raw traceback when --root points at a read-only directory.

Changes

• Refuse to create a task artifact in an existing folder unless --force is passed (exit code 2, clear stderr).
• --force reuses the folder and rewrites both task.json and notes.md atomically.
• PermissionError / generic OSError from mkdir are caught and turned into a clean non-zero exit with an actionable message.

Tests

tests/test_init_task_record.py covers: first-run creation, repeat-run refusal, --force refresh, permission-error handling.

PR

#7

Linear

• AI-2146 (this issue)
• AI-2145 (parent)