feat: launch Stripe billing flows with lifecycle hardening and analytics

add Stripe checkout, portal, webhook ingestion, and idempotent event persistence

add billing lifecycle state (grace/sync/timeline/admin visibility) and stronger entitlement handling

add analytics event tracking and admin summary APIs plus account/pricing UI integration

package-lock.json

@@ -24,6 +24,7 @@
         "react": "^19.0.0",
         "react-dom": "^19.0.0",
         "stream-json": "^2.1.0",
+        "stripe": "^22.1.1",
         "tailwind-merge": "^3.5.0",
         "vite": "^6.2.0",
         "zod": "^4.3.6"
@@ -3276,6 +3277,23 @@
         "url": "https://github.com/sponsors/uhop"
       }
     },
+    "node_modules/stripe": {
+      "version": "22.1.1",
+      "resolved": "https://registry.npmjs.org/stripe/-/stripe-22.1.1.tgz",
+      "integrity": "sha512-cmodIYP27tBkJ8G7DuGgWw0PFuemlFZbuF3Wwr1TrjFjUa3T7NIgCe6TVwX8BO2ynu+xtTuDGfHafNDCPt9lXA==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=18"
+      },
+      "peerDependencies": {
+        "@types/node": ">=18"
+      },
+      "peerDependenciesMeta": {
+        "@types/node": {
+          "optional": true
+        }
+      }
+    },
     "node_modules/tagged-tag": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/tagged-tag/-/tagged-tag-1.0.0.tgz",