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.

backend/package.json

@@ -18,6 +18,16 @@
   "author": "",
   "license": "ISC",
   "dependencies": {
+    "@opentelemetry/api": "^1.9.0",
+    "@opentelemetry/auto-instrumentations-node": "^0.52.0",
+    "@opentelemetry/exporter-logs-otlp-grpc": "^0.55.0",
+    "@opentelemetry/exporter-trace-otlp-grpc": "^0.55.0",
+    "@opentelemetry/instrumentation-pino": "^0.45.0",
+    "@opentelemetry/resources": "^1.28.0",
+    "@opentelemetry/sdk-logs": "^0.55.0",
+    "@opentelemetry/sdk-node": "^0.55.0",
+    "@opentelemetry/sdk-trace-base": "^1.28.0",
+    "@opentelemetry/semantic-conventions": "^1.28.0",
     "axios": "^1.6.0",
     "bcrypt": "^5.1.1",
     "connect-pg-simple": "^10.0.0",
@@ -27,6 +37,8 @@
     "express": "^4.18.2",
     "express-rate-limit": "^8.5.2",
     "express-session": "^1.17.3",
+    "pino": "^9.4.0",
+    "pino-http": "^10.3.0",
     "redis": "^4.6.0",
     "sqlite3": "^5.1.6",
     "web-push": "^3.6.7"