feat(pos-pwa): pOS: make TPV installable PWA and launch fullscreen

work/artifacts/POS-PWA/reviewer.json

@@ -0,0 +1,14 @@
+{
+  "feature_id": "POS-PWA",
+  "agent": "reviewer",
+  "stage": "review_gate",
+  "verdict": "APPROVED",
+  "summary": "PWA manifest + viewport added to POS app. themeColor moved to viewport export per Next.js 16 requirements.",
+  "checks": [
+    { "item": "manifest.webmanifest generated", "ok": true },
+    { "item": "No build warnings", "ok": true }
+  ],
+  "issues": [],
+  "evidence": ["cd project/apps/pos && npm run build", "git diff --check"],
+  "timestamp": "2026-08-26T18:36:20Z"
+}