chore(release): 0.14.6 — CI coverage-job flakefix + actions.cooldown race

[maltsev-dev]

Re-opened after PR #82 conflicted against origin/master (the original branch was based off a stale local master that lacked the 0.14.0-0.14.5 chain). This PR is based off origin/master @ 4878402 and contains only the four 0.14.6 changes.

Two CI-only fixes that surfaced as red runs on the 0.14.5 matrix:

1. coverage job missing pytest-rerunfailures — .github/workflows/ci.yml:74. The test matrix already installs pytest-rerunfailures>=14.0,<16.0 (lines 41-45); the coverage job did not. The @pytest.mark.rerunfailures(reruns=2) marker on tests/test_approval_timeout_field.py::TestApprovalTimeoutResolution::test_env_fallback_when_server_value_is_zero was therefore a silent no-op on the coverage leg, and the first thread-scheduling race under -n auto on shared CI runners turned the run red even though all three test legs were green. Local sequential runs pass 15/15. Marker stays the same — only the plugin install on the coverage leg is added.

2. test_is_paused_respects_cooldown window-of-zero race — tests/test_actions.py. Pre-existing 0.13.7-era flake that became 5-in-5 on the 0.14.5 runner pool. The test asserted is_paused(..., cooldown_seconds=0.0) returns False immediately after a PAUSE; the underlying is_paused computes elapsed = time.time() - paused_at and uses elapsed > cooldown (strict greater-than). On any platform where time.time() rounds the same integer as paused_at within the test body, elapsed == 0.0 and the workflow stays "paused" forever. Test now sleeps 0.01s before the post-cooldown assertion to make the check deterministic. ActionHandler.is_paused semantics unchanged.

pyproject.toml + src/nullrun/__version__.py bumped to 0.14.6 (v3.31.5 / 0.14.6) with a changelog entry covering both fixes. uv.lock added (lockfile was previously untracked; CI installs via pip so this is hygiene-only, but it keeps local uv invocations deterministic for dev work).

Verification (local, post-rebase)

• pytest tests/ --ignore=tests/contract → 1417 passed, 7 skipped in 44.11s (0 failures)
• ruff check src/ tests/ → All checks passed
• mypy src/ → Success: no issues found in 37 source files

No public API change. No on-wire change. No SDK_MIN_VERSION bump.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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