[smigolsmigol]

--watch continues to add provenance alongside the default pydantic and
pydantic-core watches. This adds repeatable --only-watch for comparisons
that need to replace those defaults, and rejects incompatible watch modes.

The issue-derived integration suite now compares pydantic-monty==0.0.19 with
pydantic-monty==0.0.20 using
pydantic/monty#621. It detects the
change from MontyRuntimeError to "reports/result.json". This is a
consumer-side release check, not a replacement for Monty's eval suite.

Local verification:

• the exact wheel passed 68 tests on each of Python 3.10 through 3.14 on Windows
• all six issue-derived integration tests passed
• Ruff passed
• branch coverage was 94.23%; changed executable lines were 100% covered