feat: SDK update for version 18.2.0

[ArnabChatterjee20k]

This PR contains updates to the SDK for version 18.2.0.

What's Changed

• Added: Realtime connections now send an x-appwrite-jwt header for authentication.
• Added: Forwarded impersonateUserId on avatars and storage file requests.

[greptile-apps]

Greptile Summary

This PR updates the Apple SDK to version 18.2.0 with two new features and a set of housekeeping changes.

• Realtime JWT auth: WebSocket upgrade requests now include an x-appwrite-jwt header when the client has a JWT configured, enabling authenticated realtime connections.
• Impersonation forwarding for media endpoints: impersonateuserid is now passed as a query parameter alongside project on all Avatars and Storage GET endpoints, allowing impersonated access when URLs are used directly (e.g., in image views where headers cannot be set).
• Deprecated Databases transaction methods: Six transaction-related methods in Databases are annotated with @available(*, deprecated) pointing developers to the TablesDB equivalents, which are confirmed present in the codebase.

Confidence Score: 5/5

All changes are additive and well-scoped; no existing call paths are altered in a breaking way.

The three functional changes (JWT header in Realtime, impersonateuserid query param forwarding, deprecation annotations) are each isolated, follow established patterns in the codebase, and the CHANGELOG accurately reflects the code. The TablesDB deprecation targets are confirmed to exist. No logic regressions or missing guards were found.

No files require special attention.

Important Files Changed

Filename	Overview
Sources/Appwrite/Client.swift	Version bumped to 18.2.0; ping() header corrected from content-type to accept; impersonate doc comments shortened; no logic changes
Sources/Appwrite/Services/Realtime.swift	Adds x-appwrite-jwt header to WebSocket upgrade when a JWT is configured; correctly reads from client.config["jwt"] with nil/empty guard
Sources/Appwrite/Services/Avatars.swift	Forwards impersonateuserid as a query param on all eight avatar GET endpoints; consistent with how project is forwarded for direct-URL access
Sources/Appwrite/Services/Storage.swift	Forwards impersonateuserid as a query param on three storage file-download/preview GET endpoints
Sources/Appwrite/Services/Databases.swift	Adds @available(*, deprecated) annotations on six transaction methods pointing to TablesDB equivalents; TablesDB.swift confirmed present in repo
CHANGELOG.md	18.2.0 entry accurately reflects the two implemented features: JWT header in Realtime and impersonateUserId forwarding
docs/examples/account/create.md	Password placeholder changed from empty string to "password"
docs/examples/account/update-password.md	Both password fields changed from empty string to "password" placeholder
docs/examples/account/update-recovery.md	Password placeholder changed from empty string to "password"

_{Reviews (3): Last reviewed commit: "chore: update Apple SDK to 18.2.0" | Re-trigger Greptile}