Refactor request matchers to objects with cassette-level scope (RequestMatcherInterface) #446

Idea

Today request matchers are plain PHP callbacks registered globally in Configuration. Two improvements have been proposed in PR #266:

1. RequestMatcherInterface — make matchers typed objects instead of raw callbacks, improving type safety and IDE support.
2. Cassette-scoped matchers — store matchers per cassette instead of globally, so different cassettes can use different matching strategies without global state changes.

Motivation

Complex matching scenarios (e.g. "match all requests to /product except when id=42, which should match on query string too") currently require a single global custom callback that encodes all the logic. Cassette-scoped matchers would allow per-request matcher overrides directly in the cassette definition.

BC break

Both changes are backwards-incompatible:

• RequestMatcherInterface replaces the current callable type
• Cassette-stored matchers change the cassette format

Target: 2.0 only.

Reference

See PR #266 for a prior implementation attempt. The PR is too old to merge directly — the codebase has changed significantly — but the concept is sound.