feat: add convex state functions for snapshot persistence

convex/schema.ts

@@ -0,0 +1,9 @@
+import { defineSchema, defineTable } from "convex/server";
+import { v } from "convex/values";
+
+export default defineSchema({
+  state_snapshots: defineTable({
+    snapshot: v.any(),
+    updatedAt: v.string(),
+  }),
+});