chore: scope desktop client build to apps/desktop-client and document regenerate route

Drop the broad path filters that triggered the desktop client build on
unrelated workspace changes, and add a swagger description for the
existing article regenerate endpoint.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitea/workflows/desktop-client-build.yml

@@ -6,11 +6,6 @@ on:
       - main
     paths:
       - "apps/desktop-client/**"
-      - "packages/**"
-      - "package.json"
-      - "pnpm-lock.yaml"
-      - "pnpm-workspace.yaml"
-      - ".gitea/workflows/desktop-client-build.yml"
   workflow_dispatch:
     inputs:
       platforms: