ci: narrow desktop build paths to avoid unnecessary runs

Restrict the pull_request paths filter to directories that actually
affect the desktop binary: cmd/agentsview/, internal/web/, desktop/,
and frontend/. Previously internal/** triggered desktop builds for
any Go change including test-only modifications.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: wesm

.github/workflows/desktop-artifacts.yml

@@ -6,8 +6,8 @@ on:
     paths:
       - 'desktop/**'
       - 'frontend/**'
-      - 'cmd/**'
-      - 'internal/**'
+      - 'cmd/agentsview/**'
+      - 'internal/web/**'
       - 'go.mod'
       - 'go.sum'
       - '.github/workflows/desktop-*.yml'