test(e2e): add playwright e2e harness

Process and API-only Playwright harness: binary and image setup, server/CLI runners, fake Docker Engine socket, read-only database inspection, secret redaction in reports, seeded fuzzing, leak detection and harness self-checks.

e2e/package.json

@@ -0,0 +1,20 @@
+{
+  "name": "dpsapi-e2e",
+  "private": true,
+  "version": "0.0.0",
+  "description": "Playwright end-to-end suite for dpsapi",
+  "scripts": {
+    "test": "playwright test",
+    "test:host": "playwright test --project=host",
+    "test:image": "playwright test --project=image",
+    "typecheck": "tsc --noEmit"
+  },
+  "engines": {
+    "node": ">=22.13"
+  },
+  "devDependencies": {
+    "@playwright/test": "1.63.0",
+    "@types/node": "26.6.4",
+    "typescript": "7.0.2"
+  }
+}