Analytics: validated palette, bars for daily spend, Empty states, es-CR

Categories fold into 'Otros' past 5 slots (fixed hue order, never
cycled); daily spending excludes future-dated Tasa Cero cuotas; rate
chart gets a legend; PageHeader with the cycle selector as action.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/app/api/v1/endpoints/analytics.py

@@ -10,6 +10,7 @@ from app.auth import get_current_user
 from app.db import get_session
 from app.models.models import Category, Transaction, TransactionType
 from app.services.budget_projection import NOT_INSTALLMENT_ANCHOR, get_cycle_range
+from app.timeutil import utcnow
 from app.services.exchange_rate import get_converted_amount_expr
 
 router = APIRouter(prefix="/analytics", tags=["analytics"])
@@ -178,6 +179,9 @@ def daily_spending(
         .where(
             Transaction.transaction_type == TransactionType.COMPRA,
             NOT_INSTALLMENT_ANCHOR,
+            # Tasa Cero generates future-dated cuotas; daily spending is
+            # about money already spent.
+            Transaction.date <= utcnow(),
         )
         .group_by(func.date(Transaction.date))
         .order_by(func.date(Transaction.date))