[BUG] — `mock_request_record.selectByQuery`: fetches `body`/`header`/`query` large columns + no pagination + no indexes

- severity: Medium; files: `mappers/mock-request-record-sqlmap.xml:45-67`; service `MockRequestRecordServiceImpl.java:83-86` (no `@Pageable`)
- description: `Base_Column_List` includes `body` (TEXT), `header`/`query`/`url` (varchar 1024) for a list query; `mock_request_record` has only PK (`schema.sql:134-147`); no index on `api_id`/`host`/`url`.
- impact: Listing transfers the full request body for every row and scans the whole table per filter.
- suggested_fix: Add `@Pageable`; add index on `api_id`; drop `body` from the list column list.
- confidence: High

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_Identified during the 2026-08-02 deep re-scan; full list in [`docs/scan2-2026-08-02/06-medium-tiers.md`](docs/scan2-2026-08-02/06-medium-tiers.md)._

Start with mappers/mock-request-record-sqlmap.xml:45-67 and MockRequestRecordServiceImpl.java:83-86, then inspect schema.sql:134-147. Confirm how the list query selects large columns and handles filtering before assessing pagination and the api_id index. Done means list results use pagination, omit body from the list columns, and support the needed index without changing detail retrieval.

Written by the indexing model from the issue text.