Drop Xamarin skeleton and add project guidelines

The Nuvolari app is being rebuilt as a Flutter project targeting Android
first and iOS later on a single codebase, so the original Xamarin.Android
skeleton no longer applies. Its files were already removed from the working
tree; this records the removal.

Adds CLAUDE.md with the golden rules that constrain the rewrite: English
code and commit messages with Italian UI via ARB, no secrets in the repo,
AdMob test IDs only, no direct polling of ARPA/DPC from the app, and no
server-side precise user locations.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Nuvolari/CLAUDE.md

@@ -0,0 +1,50 @@
+# CLAUDE.md — Radar Meteo Piemonte
+
+## Project
+Cross-platform weather-radar app for the Piedmont region (Italy). Android first, iOS later,
+single Flutter codebase. Free app monetized with AdMob (GDPR consent via UMP).
+Region-scoped now (Piemonte) but extensible to other regions via configuration.
+
+## Golden rules
+- Code, identifiers and commit messages in English. UI text in Italian via ARB localization.
+- Never commit secrets. Use .env + --dart-define; keep .gitignore updated.
+- Use ONLY AdMob TEST ad unit IDs in development.
+- Never poll ARPA/DPC servers directly from the app: always go through our backend/CDN.
+- Never store precise user locations server-side: rain notifications use geographic CELLS.
+- Do not use ARPA/DPC name, logo or the word "ufficiale" in a way implying an official app.
+
+## Architecture
+- Monorepo: /app (Flutter), /backend (Python worker), /docs (detailed docs).
+- Radar data via RadarSource interface with adapters:
+  DpcRadarSource (default, public), ArpaRadarSource (stub, awaits authorization),
+  MockRadarSource (offline/demo). Active source chosen by region config + runtime flag.
+- App reads PNG frames + manifest.json from CDN produced by the backend worker
+  (crop to Piemonte bbox, reproject to EPSG:3857).
+
+## Data sources & licenses (attribution is mandatory on the Sources screen)
+- Radar (MVP): Radar-DPC — base https://radar-api.protezionecivile.it/ ,
+  GET /findLastProductByType?type=VMI , POST /downloadProduct (GeoTIFF via presigned S3).
+  REQUIRE header `origin: https://radar.protezionecivile.it`. License CC BY-SA — credit
+  "Radar-DPC"; derivative data products must stay CC BY-SA. Docs: dpc-radar.readthedocs.io.
+- Radar (future): ARPA Piemonte (HDF5 ODIM), access via email info.meteo@arpa.piemonte.it.
+  License CC BY 4.0 — credit "Fonte: Arpa Piemonte - www.arpa.piemonte.it".
+- Forecast: MET Norway api.met.no (CC BY 4.0, commercial OK) — MANDATORY identifying
+  User-Agent (app name + contact). Fallback: ItaliaMeteo ICON-2I via MeteoHub (CC BY 4.0,
+  credit "ItaliaMeteo-ARPAE"). Do NOT use Open-Meteo free tier (non-commercial only).
+- Alerts: ARPA Piemonte XML-CAP bulletin — reproduce alert levels WITHOUT reinterpreting;
+  link the official channel.
+- Base map: OSM data via PMTiles/MapTiler — show OSM/ODbL attribution.
+- Lightning: DO NOT use Blitzortung (commercial use prohibited).
+
+## Verification loop (run after each milestone)
+- `dart format .` ; `flutter analyze` ; `flutter test` ; `flutter build appbundle`
+- Backend: `python -m pytest` ; lint. Commit frequently with clear messages.
+
+## Store / compliance targets
+- Google Play: target API 36 (Android 16) by 2026-08-31; closed testing 12 testers / 14 days;
+  Data safety section; prominent disclosure for location; signed AAB.
+- Consent: Google-certified CMP (UMP), IAB TCF 2.3, non-personalized ads if user declines.
+- iOS later: keep platform abstractions clean (ATT + privacy nutrition label to add).
+
+## Docs to maintain in /docs
+architecture.md, data-sources.md, licenses.md, stack-decisions.md, roadmap.md, privacy.md