Finish MFA v1 and refactor all tokens into separate TokenService with modified collection

backend/src/models/tokenData.ts

@@ -0,0 +1,57 @@
+import { Schema, Types, model } from 'mongoose';
+
+export interface ITokenData {
+  type: string;
+  email?: string;
+  phoneNumber?: string;
+  organization?: Types.ObjectId;
+  tokenHash: string;
+  expiresAt: Date;
+  createdAt: Date;
+  updatedAt: Date;
+}
+
+const tokenDataSchema = new Schema<ITokenData>({
+  type: {
+    type: String,
+    enum: [
+      'emailConfirmation', 
+      'emailMfa', 
+      'organizationInvitation', 
+      'passwordReset'
+    ],
+    required: true
+  },
+  email: {
+    type: String
+  },
+  phoneNumber: {
+    type: String
+  },
+  organization: { // organizationInvitation-specific field
+    type: Schema.Types.ObjectId,
+    ref: 'Organization'
+  },
+  tokenHash: {
+    type: String,
+    select: false,
+    required: true
+  },
+  expiresAt: {
+    type: Date,
+    expires: 0,
+    required: true
+  }
+}, {
+  timestamps: true
+});
+
+tokenDataSchema.index({
+  expiresAt: 1
+}, {
+  expireAfterSeconds: 0
+});
+
+const TokenData = model<ITokenData>('TokenData', tokenDataSchema);
+
+export default TokenData;