Fix the edit_file schema/runtime mismatch for memory:// resources.
- route non-empty structured edits to a server-side memory editor
- preserve path hardening, frontend access policy, expected_hash checks, Markdown validation, backups, atomic replacement, and memory-index sync
- expose the existing pure hashline primitives to the runtime
- update tool/bootstrap descriptions
- cover append, anchored replace, stale hashes, invalid Markdown rollback, and frontend skill denial
Verified with npm run typecheck and the full npm test suite.