ci: reduce CI costs by ~54% — skip desktop builds in PR/main, reduce scheduled frequency (#5090)

.github/workflows/docs.yml

@@ -6,6 +6,16 @@ on:
   push:
     branches:
       - main
+    paths:
+      # Only rebuild docs when source code changes (Dokka generates from KDoc)
+      - 'app/src/**'
+      - 'core/**/src/**'
+      - 'feature/**/src/**'
+      - 'desktop/src/**'
+      - 'build-logic/**'
+      - 'build.gradle.kts'
+      - 'settings.gradle.kts'
+      - '.github/workflows/docs.yml'
 
   # Allows you to run this workflow manually from the Actions tab
   workflow_dispatch:
@@ -29,11 +39,11 @@ permissions:
   pages: write
   id-token: write
 
-# Allow only one concurrent deployment, skipping runs queued between the run in-progress and latest queued.
-# However, do NOT cancel in-progress runs as we want to allow these production deployments to complete.
+# Allow only one concurrent deployment; cancel queued runs since only the latest
+# main state matters for documentation.
 concurrency:
   group: "pages"
-  cancel-in-progress: false
+  cancel-in-progress: true
 
 jobs:
   build-docs: