Typing @ in chat/discussion or the editor requested highlight metadata that the mention menu never renders, causing unnecessary gt index syscalls for short queries. Make U.Subscription.search call ObjectSearch while forwarding fullText and preserving filters, sorts, keys, pagination, and result mapping.

This also removes unused metadata requests from 15 audited callers: dataview/widget/library filtering, object and file pickers, block add/link menus, type/relation suggestions, and media/cover/icon libraries. The search popup keeps its separate ObjectSearchWithMeta call because it renders highlights.

Fixes JS-9874.

Validation:
- bun run typecheck passed for renderer and Electron.
- 181 tests passed across subscription, object, chat, comment, and search-match suites.
- Biome and ESLint passed for the changed file.
- git diff --check passed.