Narrow scope to radar, and put the app on a real OpenStreetMap base map

Drops forecasts, lightning, the home-screen widget and advertising. What
remains is radar on a map, the official ARPA alert bulletin, and rain
notifications.

The base map is now OpenFreeMap's Positron style: real OpenStreetMap vector
tiles with no API key, no registration, no request limits and commercial use
permitted. Every other free tier — MapTiler, Stadia, Jawg, Thunderforest —
needs a key, which is a secret to manage, a quota to outgrow and a signup to
complete before anyone can build the project, and the map is the one thing the
app cannot work without. Positron rather than Liberty or Bright because the
radar overlay has to be the loudest thing on screen, and a desaturated grey
base is built to sit under data.

Its style JSON carries no `attribution` field, so MapLibre displays no credits
by itself. The app renders them from the region config instead: the two
mandatory credits, OpenStreetMap and OpenMapTiles, go in the always-visible
bar, and OpenFreeMap's own credit — optional by their terms — is listed on the
Sources screen with the rest. The bundled offline style is still reachable with
MAP_STYLE_URL=offline, and still claims no base map attribution, because
crediting OpenStreetMap while showing it would be a false claim.

Radar-DPC stays the source. ARPA Piemonte's own radar remains a disabled stub
for two reasons that belong to the project owner, not to the code: the
real-time access link is only issued by email, and the open-data page states
the data is "gratuiti" and nothing else. Free of charge is not a licence, and
rendering those volumes into frames served from a CDN is redistribution. Both
questions go in the same email. An earlier draft of the docs recorded ARPA
radar as CC BY 4.0; the source page does not support that, so the claim is
removed rather than carried forward.

The documentation is updated throughout rather than annotated: CLAUDE.md gains
an explicit scope boundary, data-sources drops MET Norway and ISTAT and gains
the base map, licenses records that free of charge is not a licence, privacy
loses the whole advertising section, and the roadmap is renumbered so the
backend worker is next — until it exists, DpcRadarSource has nothing to read.

licenses.md keeps Open-Meteo and Blitzortung listed as excluded even though the
features that would have used them are gone: both are non-commercial-only, ads
are a plausible future, and neither should be adopted on the grounds that there
are none today.

Verified: analyze clean, 130 tests passing, and on the emulator the radar
overlay sits correctly over Piedmont on real OSM tiles with Turin, Milan and
Genoa labelled, the age reads "Aggiornato 4 minuti fa", and the Sources screen
lists all five credits with their licences.

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

Nuvolari/CLAUDE.md

@@ -1,50 +1,74 @@
-# CLAUDE.md — Radar Meteo Piemonte
+# CLAUDE.md — Nuvolari
 
 ## 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.
+Cross-platform precipitation-radar app for the Piedmont region (Italy). Android first,
+iOS later, single Flutter codebase. Region-scoped now (Piemonte) but extensible to other
+regions via configuration.
+
+## Scope
+**Radar on a map, plus official alerts and rain notifications. Nothing else.**
+
+In scope:
+- Animated precipitation radar over an OpenStreetMap base map
+- ARPA Piemonte official alert bulletin (XML-CAP), republished verbatim
+- "Rain incoming" notifications by geographic cell
+
+Explicitly out of scope — do not add these back without being asked:
+- Weather forecasts of any kind
+- Lightning
+- Home-screen widget
+- Advertising and consent flows
+
+The app is currently free with **no advertising**. Ads may return later, so prefer data
+sources that permit commercial use; do not adopt a non-commercial-only source on the
+grounds that there are no ads today.
 
 ## 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).
+- Monorepo: /app (Flutter), /backend (Python worker), /docs (detailed docs), /tool (scripts).
 - Radar data via RadarSource interface with adapters:
-  DpcRadarSource (default, public), ArpaRadarSource (stub, awaits authorization),
+  DpcRadarSource (live, reads our CDN), ArpaRadarSource (stub, awaits access),
   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/ ,
+- Radar (active): 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).
+  The rasters are on a **custom projection centred on Italy**, not EPSG:4326 or 3857, and
+  their GeoKeys are internally inconsistent — read the CRS from each file, never hardcode it.
+- Radar (future): ARPA Piemonte (HDF5 ODIM, 5-minute volumes). The data is free, but the
+  real-time access link **must be requested by email** at info.meteo@arpa.piemonte.it, and
+  ARPA states no licence — only that the data is free of charge. Both the request and the
+  licence question are the project owner's to resolve. Adapter stays a disabled stub.
+- Alerts: ARPA Piemonte XML-CAP bulletin at
+  https://www.arpa.piemonte.it/export/xmlcap/allerta.xml — reproduce alert levels WITHOUT
+  reinterpreting; link the official channel. Six level values, not four: VERDE, GIALLO,
+  ARANCIONE, ROSSO, plus BIANCO (avalanche scale out of season) and "-" (no data).
+- Base map: OpenFreeMap (https://openfreemap.org), free OSM vector tiles with no API key
+  and no request limits. Mandatory credits: "© OpenMapTiles" and
+  "© OpenStreetMap contributors" (ODbL). OpenFreeMap's own credit is optional.
 
 ## 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.
+- `tool/verify.ps1` runs all of the above and skips stages that do not exist yet.
+- Verify visually on the `nuvolari` AVD before calling a milestone done. Twice now,
+  running the app has caught defects that passing tests did not.
 
 ## Store / compliance targets
-- Google Play: target API 36 (Android 16) by 2026-08-31; closed testing 12 testers / 14 days;
+- Google Play: target API 36 (Android 16); 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).
+- No advertising, so no CMP and no IAB TCF obligations while that holds.
+- iOS later: keep platform abstractions clean (privacy nutrition label to add).
 
 ## Docs to maintain in /docs
 architecture.md, data-sources.md, licenses.md, stack-decisions.md, roadmap.md, privacy.md