docs: add missing Swift client functions to specification (supabase#37928)

* docs: add missing Swift client functions to specification

Add comprehensive documentation for 26 previously undocumented Swift functions:

- feat: add 17 database filter functions (eq, neq, gt, gte, lt, lte, like, ilike, is, in, contains, containedBy, overlaps, range functions, textSearch)
- feat: add 5 Admin API functions (getUserById, listUsers, createUser, updateUserById, inviteUserByEmail)
- feat: add 2 session management functions (startAutoRefresh, stopAutoRefresh)
- feat: add 2 storage signed URL functions (createSignedUploadUrl, uploadToSignedUrl)

These functions exist in the Swift library but were missing from the documentation spec,
causing a perceived gap compared to the JavaScript client. All additions include proper
Swift syntax examples, async/await patterns, and comprehensive usage documentation.

Closes alignment gap between Swift and JavaScript client documentation.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

* fix params

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Co-authored-by: Claude <[email protected]>

Author: Guilherme Souza