chore: prepare Server 1.9.0

[Priveetee]

Summary

• Release the current Server line as TypeType 1.9.0.
• Carry the backend modularization and the accumulated account, portability, subscription, and playback work into the release.

Production behavior

• Extends server APIs and services for YouTube SABR/live recovery, BiliBili sessions, account/profile flows, Takeout, subscriptions, and access management.
• Updates the OpenAPI contract alongside the affected routes.

Deployment requirements

• Deploy with the coordinated TypeType 1.9.0 component set and the Server image built from the merged revision.

Runtime verification

• The main-branch Docker workflow completed successfully.
• Production runtime verification remains pending the rollout.

Tests

• Pull request CI, coverage, and OpenAPI checks passed.

Rollback

• Restore the previous Server image reference and the matching TypeType stack revision.