feat(fullstack): implement observability and redesign frontend UI

This commit introduces comprehensive observability for both backend and frontend, alongside a major UI/UX overhaul to align with modern design standards (Material 3 inspired) and improve localization.

Backend changes:
- Integrated OpenTelemetry SDK for distributed tracing.
- Added Pino for structured JSON logging with OTel instrumentation for trace/span correlation.
- Configured OTLP exporters to route traces and logs to Grafana Alloy.
- Updated docker-compose to include necessary environment variables for observability.

Frontend changes:
- Integrated Grafana Faro for Real User Monitoring (RUM), capturing Web Vitals, JS errors, and user interactions.
- Redesigned the entire UI using a new color palette and Material 3 design principles.
- Refactored component architecture (App, Home, Search, Scanner, Profile, Alerts views) for better state management and navigation.
- Improved mobile UX with a redesigned Bottom Navigation bar and Top Bar.
- Localized the interface to Spanish (es).
- Updated assets, icons, and PWA configuration (manifest, icons).
- Refactored CSS to use a centralized design token system (CSS variables).

Observability enables better debugging and performance monitoring across the entire stack.

docker-compose.yml

@@ -32,6 +32,12 @@ services:
       DATABASE_PATH: /app/data/database.sqlite
       FARMACIAS_WEBHOOK_URL: ${FARMACIAS_WEBHOOK_URL:-}
       PG_URL: postgresql://farmafinder:${PG_PASSWORD:-change-me-in-production}@postgres:5432/farmafinder
+      # OpenTelemetry — exported via OTLP gRPC to the shared Alloy collector
+      OTEL_SERVICE_NAME: farmafinder-backend
+      OTEL_EXPORTER_OTLP_ENDPOINT: http://host.docker.internal:4317
+      OTEL_TRACES_EXPORTER: otlp
+      OTEL_LOGS_EXPORTER: otlp
+      OTEL_RESOURCE_ATTRIBUTES: service.namespace=farmafinder
     volumes:
       - backend_data:/app/data
     depends_on:
@@ -40,7 +46,13 @@ services:
 
   frontend:
     image: git.hacecalor.net/ichitux/farmafinder-frontend:latest
-    build: ./frontend
+    build:
+      context: ./frontend
+      args:
+        VITE_FARO_ENDPOINT: ${VITE_FARO_ENDPOINT:-http://localhost:4318}
+        VITE_FARO_APP_NAME: ${VITE_FARO_APP_NAME:-farmafinder-frontend}
+        VITE_FARO_ENV: ${VITE_FARO_ENV:-production}
+        VITE_FARO_APP_VERSION: ${VITE_FARO_APP_VERSION:-1.0.0}
     restart: unless-stopped
     ports:
       - "3000:80"