docs: Remove Doorking and Linear brand guides entirely

These brands are no longer supported.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: louis-pre

docs/brand-guides/SUMMARY.md

@@ -87,8 +87,6 @@
   * [Sandbox Brivo Access](brivo-access/brivo-access-sample-data.md)
 * [ControlByWeb Relays](controlbyweb-relays/README.md)
   * [Sandbox ControlByWeb Relays](controlbyweb-relays/controlbyweb-relays-sample-data.md)
-* [Doorking Callboxes](doorking-callboxes/README.md)
-  * [Sandbox Doorking Callboxes](doorking-callboxes/doorking-sample-data.md)
 * [Dormakaba Ambiance Access Control System](dormakaba-ambiance-access-control-system/README.md)
   * [Dormakaba Ambiance Setup Guide](dormakaba-ambiance-access-control-system/dormakaba-ambiance-setup-guide.md)
   * [Sandbox Dormakaba Ambiance Access Control System](dormakaba-ambiance-access-control-system/sandbox-dormakaba-ambiance-access-control-system.md)
@@ -131,8 +129,6 @@
   * [Programming Code-Based Latch Credentials](latch-access-control-system/programming-code-based-latch-credentials.md)
   * [Programming Latch ACS Mobile Credentials](latch-access-control-system/programming-latch-acs-mobile-credentials.md)
   * [Sandbox Latch Access Control System](latch-access-control-system/sandbox-latch-access-control-system.md)
-* [Linear Callboxes](linear-callboxes/README.md)
-  * [Sandbox Linear Callboxes](linear-callboxes/linear-sample-data.md)
 * [Lockly Locks](lockly-locks/README.md)
   * [Lockly Setup Guide](lockly-locks/lockly-setup-guide.md)
   * [Creating Lockly Offline Access Codes](lockly-locks/creating-lockly-offline-access-codes.md)