extend unsafe assertion diagnostic to streams and layers

[mattiamanzati]

Summary

• Port Effect-TS/language-service@b98c573 for unsafe type assertion diagnostics.
• Extend unsafeEffectTypeAssertion to detect unsafe Stream and Layer assertions in addition to Effect.
• Update diagnostic/codefix wording, metadata/schema/README output, examples, changeset, and v3/v4 baselines.

Validation

• pnpm setup-repo
• pnpm lint
• pnpm check
• pnpm test