Phase 6: Translate User Pages - exchange, trades, invites, profile

- Expand exchange.json with all exchange page strings (page, steps, detailsStep, bookingStep, confirmationStep, priceDisplay)
- Create trades.json translation files for es, en, ca
- Create invites.json translation files for es, en, ca
- Create profile.json translation files for es, en, ca
- Translate exchange page and all components (ExchangeDetailsStep, BookingStep, ConfirmationStep, StepIndicator, PriceDisplay)
- Translate trades page (titles, sections, buttons, status labels)
- Translate invites page (titles, sections, status badges, copy button)
- Translate profile page (form labels, hints, placeholders, messages)
- Update IntlProvider to load all new namespaces
- All frontend tests passing

frontend/locales/ca/exchange.json

@@ -8,10 +8,70 @@
   },
   "direction": {
     "buy": "COMPRAR BTC",
-    "sell": "VENDRE BTC"
+    "sell": "VENDRE BTC",
+    "buyShort": "Comprar BTC",
+    "sellShort": "Vendre BTC"
   },
   "transferMethod": {
     "onchain": "Onchain",
     "lightning": "Lightning"
+  },
+  "page": {
+    "title": "Intercanviar Bitcoin",
+    "subtitle": "Compra o ven Bitcoin amb una prima del 5%",
+    "viewExistingTrade": "Veure la teva operació existent →"
+  },
+  "steps": {
+    "details": "Detalls de l'Intercanvi",
+    "booking": "Reservar Cita",
+    "confirm": "Confirmar"
+  },
+  "detailsStep": {
+    "paymentMethod": "Mètode de Pagament",
+    "required": "*",
+    "lightningThreshold": "Els pagaments Lightning només estan disponibles per importants fins a €{max}",
+    "amount": "Quantitat (EUR)",
+    "summaryBuy": "Compres {sats}, vens {eur}",
+    "summarySell": "Compres {eur}, vens {sats}",
+    "continueToBooking": "Continuar a Reserva"
+  },
+  "bookingStep": {
+    "yourExchange": "El Teu Intercanvi",
+    "edit": "Editar",
+    "buy": "Comprar",
+    "sell": "Vendre",
+    "receiveVia": "Rebre via",
+    "sendVia": "Enviar via",
+    "selectDate": "Seleccionar una Data",
+    "existingTradeWarning": "Ja tens una operació reservada en aquest dia. Només pots reservar una operació per dia.",
+    "viewExistingTrade": "Veure la teva operació existent →",
+    "availableSlots": "Espais Disponibles per a",
+    "loadingSlots": "Carregant espais...",
+    "noSlots": "No hi ha espais disponibles per a aquesta data"
+  },
+  "confirmationStep": {
+    "appointment": "Cita",
+    "edit": "Editar",
+    "confirmTrade": "Confirmar Operació",
+    "time": "Hora:",
+    "direction": "Direcció:",
+    "eur": "EUR:",
+    "btc": "BTC:",
+    "rate": "Taxa:",
+    "payment": "Pagament:",
+    "receiveVia": "Rebre via",
+    "sendVia": "Enviar via",
+    "booking": "Reservant...",
+    "priceStale": "Preu Desactualitzat",
+    "confirmBuy": "Confirmar Compra",
+    "confirmSell": "Confirmar Venda",
+    "back": "Enrere"
+  },
+  "priceDisplay": {
+    "loading": "Carregant preu...",
+    "market": "Mercat:",
+    "ourPrice": "El nostre preu:",
+    "updated": "Actualitzat",
+    "stale": "(desactualitzat)"
   }
 }