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/db/migrations/016_add_payment_method_change_count.sql

@@ -0,0 +1,13 @@
+-- Adicionar campo para contar trocas de método de pagamento
+ALTER TABLE purchase_intentions 
+ADD COLUMN IF NOT EXISTS payment_method_change_count INT DEFAULT 0;
+
+-- Atualizar registros existentes para 0
+UPDATE purchase_intentions 
+SET payment_method_change_count = 0 
+WHERE payment_method_change_count IS NULL;
+
+-- Adicionar índice para queries de verificação
+CREATE INDEX IF NOT EXISTS idx_purchase_intentions_buyer_listing 
+ON purchase_intentions(buyer_id, listing_id, status);
+