release: 0.6.1 — Layer-1/2/3 ('give the user a chance')

[maltsev-dev]

Summary

Bumps version 0.6.0 → 0.6.1 and adds the release-notes entry.
The functional work landed in the merged PRs #31 (Layer-1) and
#32 (Layer-2/3); this PR is the release label + CHANGELOG.

What's in 0.6.1

All three layers of the "give the user a chance" design, on top of
the 0.6.0 P0 hardening pass:

Layer	What	Public API
1 — structured exception hierarchy	NullRunError base + 5 typed subclasses (ConfigError, AuthError, BackendError, BudgetError, ToolBlockedError) with error_code / user_action / retryable / docs_url / cause	nullrun.NullRunError, NullRunAuthError, NullRunConfigError, NullRunBackendError, NullRunBudgetError, NullRunToolBlockedError, WorkflowKilledInterrupt
2 — global error hook	nullrun.on_error(hook) fires for every structured NullRunError before it propagates; multiple hooks fire in registration order; hook exceptions are caught and logged at DEBUG; has_hooks() short-circuit keeps the hot path zero-cost	nullrun.on_error
3 — runtime snapshot	nullrun.status() returns a frozen NullRunStatus dataclass with one of four headline states (ok / degraded / offline / misconfigured); raises NullRunConfigError (NR-C004) if no runtime has been init()'d; never lazily creates a runtime	nullrun.status

Per-code docs: docs/errors/ (15 per-code pages + README index).

TestPyPI yank — manual step (REQUIRED before re-running publish)

The previous 0.6.0 on TestPyPI (uploaded 2026-06-23, before #31
and #32 landed) cannot be silently overwritten — TestPyPI rejects
400 File already exists for any filename reuse regardless of
content hash (see https://test.pypi.org/help/#file-name-reuse).

The publish-test workflow must yank the existing 0.6.0 first.
Easiest path — web UI:

1. Go to https://test.pypi.org/project/nullrun/0.6.0/#history
2. Click Manage → Yank release
3. Confirm

After the yank, re-run Actions → publish-test → Run workflow on
master (or wait for this PR to merge and run on master).

If you prefer the CLI (requires a TestPyPI API token with
project scope — not stored in this repo's secrets, only
Trusted-Publishing is wired):

pip install twine
twine yank nullrun -r testpypi -v 0.6.0

Verification (already done locally on master HEAD)

Check	Result
pytest	926 passed, 13 skipped
ruff check src/ tests/	All checks passed
mypy src/	No issues found in 26 source files

Files in this PR

• pyproject.toml — version = "0.6.1"
• src/nullrun/__version__.py — __version__ = "0.6.1"
• CHANGELOG.md — ## [0.6.1] — 2026-06-24 entry

After merge

1. Yank 0.6.0 on TestPyPI (web UI; see above).
2. Re-run publish-test workflow on master.
3. Verify the new 0.6.1 upload succeeds:
   pip install -i https://test.pypi.org/simple/ nullrun==0.6.1.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!