P0: reject register() after close_all() with RuntimeError.
P1: catch CancelledError in close_all(), use WeakKeyDictionary for
cancellation_reasons to prevent memory leak, guard StateManager
update_state/reset/load_checkpoint/time_travel after close().
P2: contextlib.suppress in __del__ for partial construction, re-cancel
pending tasks in cleanup_tasks_async, handle late tasks added during
await window, guard AcpEventQueue.publish() after close with _is_closed
flag and is_closed property, fix ASV TimeRegisterBatch crash.
Tests: 5 new Behave scenarios (T1-T4 + is_closed), log handler and
event loop cleanup in after_scenario (T5-T6).
Docs: async_safety.md updated for register-after-close and state
mutation guards.
ISSUES CLOSED: #321
Each behave-parallel worker previously resolved to the same file-based
SQLite database (cleveragents.db or .cleveragents/db.sqlite) because
before_scenario removed the CLEVERAGENTS_DATABASE_URL env var and the
fallback paths are shared across processes. Under parallel execution
this caused intermittent 'database is locked' and duplicate-project
errors—most visibly in the coverage_report nox session.
Replace the env-var removal in before_scenario with unique temp database
paths via tempfile.mktemp(), giving every scenario its own isolated
database file. Temp files are cleaned up in after_scenario.
Also fix cli_streaming_steps.py where a Background + duplicate Given
sequence triggered a duplicate project name collision, and update
coverage_boost_steps.py so Settings-default assertions explicitly clear
the env vars before testing pydantic defaults.