feat: sync savings chat history with convex

convex/schema.ts

@@ -9,6 +9,12 @@ const loanStatus = v.union(
   v.literal("abbezahlt"),
   v.literal("pausiert"),
 );
+const chatRole = v.union(v.literal("user"), v.literal("assistant"));
+const chatToolTrace = v.object({
+  name: v.string(),
+  inputSummary: v.string(),
+  resultSummary: v.string(),
+});
 
 export default defineSchema({
   ...authTables,
@@ -175,4 +181,25 @@ export default defineSchema({
     isDecoupled: v.optional(v.boolean()),
     submittedTan: v.optional(v.string()),
   }).index("by_user", ["userId"]),
+
+  chatSessions: defineTable({
+    userId: v.id("users"),
+    title: v.string(),
+    createdAt: v.number(),
+    updatedAt: v.number(),
+    messageCount: v.number(),
+    legacyLocalId: v.optional(v.string()),
+    isDeleted: v.boolean(),
+  })
+    .index("by_user_deleted_updated", ["userId", "isDeleted", "updatedAt"])
+    .index("by_user_legacyLocalId", ["userId", "legacyLocalId"]),
+
+  chatMessages: defineTable({
+    userId: v.id("users"),
+    sessionId: v.id("chatSessions"),
+    role: chatRole,
+    content: v.string(),
+    createdAt: v.number(),
+    toolTrace: v.optional(v.array(chatToolTrace)),
+  }).index("by_user_session_created", ["userId", "sessionId", "createdAt"]),
 });