Parent: #3401

Summary

Add a cross-binding regression matrix so nested field support remains consistent across Python sync/async, Rust, Node, local tables, and remote tables.

Scope

• Cover nested scalar, vector, and FTS index lifecycle where each binding exposes the API.
• Cover create, list, stats, search/filter, append, and optimize behavior.
• Cover field-name edge cases: mixed case, special characters, top-level literal dots, nested special characters, and same-name leaves.
• Reuse the same semantic matrix across bindings instead of adding unrelated one-off tests.

Acceptance criteria

• Python sync/async, Rust, and Node have nested field smoke coverage.
• Local and remote tables agree on canonical field path behavior.
• The matrix includes rowId, `row-id`, `a.b`, MetaData.userId, and `meta-data`.`user-id`.
• Tests fail if list/describe/stats regress to leaf-only field names.