feat(client-core): wire extended /v1/meta and narrow Meta types by extended flag

[jagodin]

Check List

• Tests have been run in packages where changes have been made if available
• Linter has been run for changed code
• Tests for the changes have been added if not covered yet
• Docs have been added / updated if required

Issue Reference this PR resolves

Description of Changes Made

Exposes extended /v1/meta from @cubejs-client/core in a way that matches the API gateway (the extended query parameter is presence-based, so the client only sends extended: true when requested and never sends extended=false).

• CubeApi.meta: MetaMethodOptions with optional extended; request params include extended: true only when options.extended === true; overloads return Meta<MetaResponse> for plain meta and Meta<MetaResponseExtended> when extended: true.
• Types: Split plain vs extended shapes (CubePlain / CubeExtended, MetaResponse / MetaResponseExtended, plain member types where extended SQL-related fields are omitted). Cube remains an alias for CubePlain. Meta is generic over the meta response type; helpers such as MetaCubeOf, CubesMapFromMeta, and TCubeMemberByTypeForMeta support typed access.
• Tests: CubeApi.test.ts covers transport params for default / extended: false (no extended key) vs extended: true, including combined signal and baseRequestId.