chore(ci): run main workflows on self-hosted runners (#602)

Split PR CI (GitHub-hosted) from main push CI/deploy (page-agent-trusted).

.github/workflows/ci.yml

@@ -3,27 +3,21 @@ permissions:
   contents: read
 
 on:
-  push:
-    branches: [main]
   pull_request:
     branches: [main]
 
 jobs:
   test:
     runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        node-version: [24]
-
     steps:
       - uses: actions/checkout@v7
         with:
           fetch-depth: 0
 
-      - name: Setup Node.js ${{ matrix.node-version }}
+      - name: Setup Node.js
         uses: actions/setup-node@v6
         with:
-          node-version: ${{ matrix.node-version }}
+          node-version: 24
           cache: 'npm'
 
       - name: Install dependencies

.github/workflows/deploy-website.yml

@@ -3,10 +3,11 @@ name: Deploy Website
 on:
   push:
     branches: [main]
+  workflow_dispatch:
 
 jobs:
   deploy:
-    runs-on: ubuntu-latest
+    runs-on: page-agent-trusted
     permissions:
       contents: read
       pages: write

.github/workflows/main-ci.yml

@@ -0,0 +1,30 @@
+# Runs only for code already on main, on the self-hosted runner.
+# PR-triggered CI must stay on GitHub-hosted runners (see ci.yml).
+name: Main CI
+permissions:
+  contents: read
+
+on:
+  push:
+    branches: [main]
+  workflow_dispatch:
+
+jobs:
+  test:
+    runs-on: page-agent-trusted
+    steps:
+      - uses: actions/checkout@v7
+        with:
+          fetch-depth: 0
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v6
+        with:
+          node-version: 24
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: CI checks
+        run: node scripts/ci.js