fix: key lifecycle state by Click context

[codeforester]

Fixes #383

Lifecycle state is keyed by the Click context object, preventing state from being attributed to a different context after object-ID reuse. Regression coverage includes chained context teardown.

Branch maintenance

Refs #426. Targets main.

The branch was refreshed without rewriting history to include main at a576cc279739eae5e4cfc33ffab2a7fb56de24de. The already-merged calibration patch is absent from this review diff; the original issue patch is preserved.

Current-head validation

At 8de1e67df9808ed7d116b8823945daa13496940b: uv lock freshness and baseline, runtime, strict typing, style, and contracts passed locally with all declared extras. Runtime result: 610 passed, 1 warning, 262 subtests passed in 7.79s.

Hosted checks: 7/7 required checks passed; 0 checks pending; 0 unsuccessful checks at 2026-10-04T14:19:40.760978+00:00. See the PR Checks tab and #426 for subsequent results.

[codeforester]

Branch maintenance complete.

• Synced with current main (including feat: record telemetry span outcomes #402) in merge commit 0d73169; no conflicts remained.
• Review follow-ups from 4288816 are present: real chain=True teardown coverage and documented invocation-scoped retention.
• Local full suite, Ruff, formatting, and strict mypy pass.
• Hosted checks: 26 successful, 4 skipped, 0 failed; PR is mergeable/clean.

Left open for review; not merged.