fix(gsd): handle retentionDays=0 on Windows + run windows-portability on PRs (#2460)

Two changes:

1. pruneActivityLogs: when retentionDays is 0, skip mtime comparison and
   unconditionally remove all files except highest-seq. On Windows, NTFS
   timestamp resolution meant freshly-created files could have mtime >=
   Date.now() at cutoff calculation, so none were pruned.

2. CI: remove the push-to-main gate on windows-portability so it runs on
   PRs too — catches Windows failures before merge instead of after.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -145,8 +145,7 @@ jobs:
     timeout-minutes: 15
     needs: detect-changes
     if: >-
-      needs.detect-changes.outputs.docs-only != 'true' &&
-      github.event_name == 'push' && github.ref == 'refs/heads/main'
+      needs.detect-changes.outputs.docs-only != 'true'
     runs-on: blacksmith-4vcpu-windows-2025
 
     steps:

src/resources/extensions/gsd/activity-log.ts

@@ -153,6 +153,7 @@ export function pruneActivityLogs(activityDir: string, retentionDays: number): v
     const cutoff = Date.now() - retentionDays * 86_400_000;
     for (const entry of entries) {
       if (entry.seq === maxSeq) continue;  // always preserve highest-seq
+      if (retentionDays === 0) { try { unlinkSync(entry.filePath); } catch { /* skip */ } continue; }
       try {
         const mtime = statSync(entry.filePath).mtimeMs;
         if (Math.floor(mtime) <= cutoff) unlinkSync(entry.filePath);