Add configurable mutation type filtering

[nabi-noor]

Adds stable dotted names to the mutation registry and a disable_mutation_types configuration option. Exact names disable one mutation, while prefixes disable a group; for example, string.lower removes only lowercase literal mutations and string removes every string mutation.

The filtering happens before an operator runs. Configuration changes also invalidate cached mutant verdicts because removing a mutation can shift the numeric IDs of later mutants in the same function.

This PR intentionally focuses on disabling types, which solves the reported equivalent-mutant problem without defining potentially surprising precedence between simultaneous allow and deny lists. An enable/override policy can be added separately once those semantics are agreed.

Documentation lists the available names and shows how to disable the two case-flip mutations. Unit coverage exercises exact, grouped, unrelated, invalid, and cache-change behavior; the existing config E2E project verifies that both case flips disappear while the useful string-wrap mutant remains.

Verified with uv run pytest (403 passed, 2 skipped) and uv run pre-commit run --all-files (all hooks passed).

AI assistance disclosure: I used OpenAI Codex while implementing and reviewing this change. The commit includes the corresponding co-author attribution.

Closes #577