ci(test): use Node 24 (repo requires >=24, engine-strict) and trigger on main

The sh1pt node-pnpm-test pack pinned Node 22, which fails pnpm install under our
engine-strict node>=24. Also retarget master -> main.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: ralyodio

.github/workflows/test.yml

@@ -7,7 +7,7 @@ name: test
 on:
   pull_request:
   push:
-    branches: [master]
+    branches: [main]
 
 permissions:
   contents: read
@@ -26,7 +26,7 @@ jobs:
 
       - uses: actions/setup-node@v4
         with:
-          node-version: 22
+          node-version: 24
           cache: pnpm
 
       - run: pnpm install --frozen-lockfile