Input Rule Factory Entrypoint Cleanup

Goal

Remove the remaining handwritten rule entrypoints in @platejs/math and @platejs/link so createRuleFactory(...) stays the only public constructor authority for package-owned input rules.

Scope

• packages/math/src/lib/MathRules.ts
• packages/link/src/lib/LinkRules.ts
• affected tests and docs only if the public surface changes

Constraints

• Keep current user-facing ergonomics where possible.
• Do not reintroduce manual option wrapper types that drift from factory runtime fields like enabled and priority.
• Preserve feature ownership. Core should not absorb link/math semantics.

Plan

1. Refactor MathRules to remove the handwritten union wrapper.
2. Refactor LinkRules.autolink to remove the handwritten variant wrapper.
3. Update affected tests/docs if the public API shape changes.
4. Verify with build, typecheck, focused tests, and lint.

Relevant Learnings

• docs/solutions/best-practices/input-rules-should-register-explicit-rule-instances-while-packages-export-markdown-families.md
• docs/solutions/best-practices/input-rule-context-should-provide-lazy-snapshot-getters.md
• docs/solutions/best-practices/block-fence-input-rules-should-split-fence-matching-from-feature-apply.md