feat: #45 meta de poupança configurável + conquistas genéricas

- Nova tabela user_settings com savings_goal_pct (default 40%)
- API GET /api/settings, PUT /api/settings
- DashboardService inclui savings_goal_pct no payload
- DashboardHandler dispara savings_checked com goal configurado
- GameService.NotifyAction: checa pct >= goal (sem hardcode de 40%)
- SettingsView: painel META DE POUPANÇA com input configurável
- HomeView: widget mostra meta dinâmica (META: X%) e usa savingsGoal
- stores/settings.ts: store com fetch e update

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

apps/api/internal/handler/settings.go

@@ -0,0 +1,44 @@
+package handler
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"financeiro-carvalho/internal/model"
+	"financeiro-carvalho/internal/service"
+)
+
+type SettingsHandler struct {
+	svc *service.SettingsService
+}
+
+func NewSettingsHandler(svc *service.SettingsService) *SettingsHandler {
+	return &SettingsHandler{svc: svc}
+}
+
+func (h *SettingsHandler) Get(w http.ResponseWriter, r *http.Request) {
+	s, err := h.svc.Get(r.Context())
+	if err != nil {
+		respondError(w, http.StatusInternalServerError, "failed to get settings")
+		return
+	}
+	respondJSON(w, http.StatusOK, s)
+}
+
+func (h *SettingsHandler) Update(w http.ResponseWriter, r *http.Request) {
+	var in model.UserSettings
+	if err := json.NewDecoder(r.Body).Decode(&in); err != nil {
+		respondError(w, http.StatusBadRequest, "invalid JSON")
+		return
+	}
+	out, err := h.svc.Update(r.Context(), in)
+	if err != nil {
+		if err == service.ErrInvalidSavingsGoal {
+			respondError(w, http.StatusUnprocessableEntity, err.Error())
+			return
+		}
+		respondError(w, http.StatusInternalServerError, "failed to update settings")
+		return
+	}
+	respondJSON(w, http.StatusOK, out)
+}