Add viam-server reference page, move aliases from _index.md

Copies existing viam-server content from operate/reference/viam-server/
to reference/viam-server.md. All aliases moved from reference/_index.md
to the dedicated page. Body links updated to new-IA paths.

The #maintenance-window anchor matches what the Viam app links to from
the maintenance card and version-control documentation.

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

Author: shannonbradshaw

docs/reference/_index.md

@@ -49,31 +49,18 @@ aliases:
   - /reference/changelog/
   - /dev/reference/changelog/
   - /reference/platform/
-  - /reference/platform/viam-server/
-  - /reference/platform/viam-server/manage-viam-server/
-  - /reference/platform/viam-server/debug-endpoints/
   - /reference/platform/viam-agent/
   - /reference/platform/viam-agent/manage-viam-agent/
   - /reference/platform/viam-micro-server/
-  - /operate/reference/viam-server/
-  - /operate/reference/viam-server/manage-viam-server/
-  - /operate/reference/viam-server/debug-endpoints/
-  - /operate/reference/viam-server/local-configuration-file/
   - /operate/install/setup-micro/
   - /operate/reference/viam-micro-server/
   - /operate/reference/viam-micro-server/viam-micro-server-troubleshooting/
-  - /internals/rdk/
-  - /architecture/rdk/
-  - /architecture/viam-server/
-  - /internals/local-configuration-file/
   - /installation/manage-viam-agent/
   - /installation/microcontrollers/
   - /installation/prepare/microcontrollers/
   - /installation/viam-micro-server-setup/
   - /installation/update/
-  - /installation/manage-viam-server/
   - /build/micro-rdk/
   - /get-started/installation/microcontrollers/
-  - /get-started/installation/manage-viam-server/
   - /operate/get-started/setup-micro/
 ---