feat(market): add Minha Intenções tab with panel, hook, and badge

- Introduced "Minhas Intenções" tab visible only to logged-in users.
- Integrated MyPurchaseIntentionsPanel and useMyPurchaseIntentions hook.
- Added tab badge showing count of pending intentions.
- Extended session API to include user’s main character for downstream features.

lib/mongodb/models/Message.ts

@@ -0,0 +1,81 @@
+/**
+ * Model Message - Representa uma mensagem em um chat
+ */
+
+import mongoose, { Schema, model, models } from "mongoose";
+
+export interface IMessage {
+  chat_id: string; // Referência ao chat
+  sender_id: number; // ID do remetente (PostgreSQL)
+  content: string; // Conteúdo da mensagem (sanitizado)
+  created_at: Date;
+  read_at: Date | null; // Quando foi lida
+  edited_at: Date | null; // Se foi editada
+  deleted_at: Date | null; // Soft delete
+  
+  // Metadados
+  message_type: "text" | "system"; // System para mensagens automáticas
+  metadata?: {
+    listing_id?: number;
+    action?: "listing_updated" | "listing_sold" | "price_changed";
+  };
+}
+
+const MessageSchema = new Schema<IMessage>(
+  {
+    chat_id: {
+      type: String,
+      required: true,
+      index: true,
+    },
+    sender_id: {
+      type: Number,
+      required: true,
+      index: true,
+    },
+    content: {
+      type: String,
+      required: true,
+      maxlength: 1000,
+      trim: true,
+    },
+    created_at: {
+      type: Date,
+      default: Date.now,
+      index: true,
+    },
+    read_at: {
+      type: Date,
+      default: null,
+    },
+    edited_at: {
+      type: Date,
+      default: null,
+    },
+    deleted_at: {
+      type: Date,
+      default: null,
+    },
+    message_type: {
+      type: String,
+      enum: ["text", "system"],
+      default: "text",
+    },
+    metadata: {
+      type: Schema.Types.Mixed,
+      default: null,
+    },
+  },
+  {
+    timestamps: false, // Usamos campos manuais
+    collection: "messages",
+  }
+);
+
+// Índices compostos para queries eficientes
+MessageSchema.index({ chat_id: 1, created_at: -1 }); // Para buscar mensagens de um chat ordenadas
+MessageSchema.index({ chat_id: 1, sender_id: 1, created_at: -1 });
+MessageSchema.index({ sender_id: 1, created_at: -1 });
+
+export const Message = models.Message || model<IMessage>("Message", MessageSchema);
+