feat(migrate): add interactive migration wizard

- Add MigrationWizard for guided schema changes
- Support add/update/remove field operations
- Algorithm-specific datatype prompts (SVS-VAMANA vs HNSW/FLAT)
- SVS-VAMANA params: GRAPH_MAX_DEGREE, COMPRESSION
- HNSW params: M, EF_CONSTRUCTION
- Normalize SVS_VAMANA -> SVS-VAMANA input
- Preview patch as YAML before finishing

Author: nkanu17