refactor(whatsrust): extract action wrappers

[Andiveli]

Summary

• Extract reaction, edit, and revoke wrappers from the whatsrust facade.
• Preserve argument validation, CString ownership, bridge status mapping, public signatures, and ABI behavior.

Changes

• Added whatsrust/src/actions.rs.
• Re-exported the four public action wrapper entry points from lib.rs.
• Kept conversion helpers available to the existing facade tests without changing their behavior.

Chain Context

• Start: PR refactor(whatsrust): extract media wrappers #314 (refactor/whatsrust-media-wrappers).
• End: action wrappers isolated; this completes the requested five-slice chain.
• Dependency: immediate parent is PR refactor(whatsrust): extract media wrappers #314; no merge or CI wait requested.
• Diagram: #301 -> #311 -> #312 -> #313 -> #314 -> 📍 #315.
• Deferred: Cargo compilation/tests are intentionally deferred per task instructions; only formatting/source/diff checks were run.
• Rollback: revert commit ce2a3e5 / remove actions.rs and restore the action wrapper block in lib.rs; no unrelated behavior changes.

Testing

• cargo fmt --check
• git diff --check
• Source and authored-line budget checks
• Cargo tests/build (deferred; no Cargo build/test command run)
• Manual runtime testing (not applicable to this mechanical extraction)

Closes #310