Federate official Belgium data sources

docs/DATA_SOURCES.md

@@ -751,9 +751,37 @@ inferred from these plan zones.
 
 The coverage resolver reports a theme `operational` only when a matching
 `ready` Dataset exists in the selected project. Implemented acquisition
-without project materialization is `partial`; Walloon, Brussels, Statbel and
-MDK families remain `not_configured` until their own bounded adapters and
-source-specific metric contracts are implemented.
+without project materialization is `partial`. Statbel is an operator-managed
+national source. SPW/PICC and UrbIS are bounded API sources for their explicit
+themes and zones. MDK remains `not_configured` while its strict-TLS readiness
+probe fails.
+
+The governed Statbel operator supports `belgium` as a first-class scope. It
+uses the retained NGI Belgium boundary, retains every statistical-sector row
+and requires the existing plan -> stage -> named review -> checksum-confirmed
+apply process. Flanders, Wallonia, Brussels and bounded municipality
+population queries therefore derive from one reviewed national edition rather
+than mutually incompatible regional imports. No edition is downloaded or
+promoted during application startup.
+
+## Wallonia PICC and Brussels UrbIS
+
+The official-vector registry exposes bounded, source-specific regional
+baselines:
+
+- SPW/PICC MapServer layers 11 (buildings), 21 (road axes), 28
+  (hydrographic axes) and 30 (hydrographic surfaces) for Wallonia;
+- Paradigm UrbIS `Buildings` and `CadastralParcels` WFS collections for the
+  Brussels-Capital Region.
+
+SPW queries use stable `OBJECTID` paging and request EPSG:4326 output while
+retaining EPSG:3812 as the native source CRS. UrbIS responses use EPSG:31370,
+stable `INSPIRE_ID` paging and are transformed only after exact regional
+clipping. Both adapters enforce bbox dimensions, page/feature/response limits,
+strict HTTPS host/path validation, geometry contracts and persisted coverage
+Areas. They persist only through `DatasetService`; the browser never contacts
+either provider directly. Cross-zone selections remain split by authority and
+metric semantics.
 
 ## Bathymetry, inland profiles and maritime scope
 
@@ -768,10 +796,10 @@ The following sources are audited but not yet operational:
 
 - MDK Dieptemodel Belgisch Continentaal Plat/Noordzee: 20 x 20 m continuous
   raster in LAT, exposed through WCS/WMTS. GeoIntel now has a strict-TLS,
-  read-only GetCapabilities probe. On 2026-07-17 the official metadata
-  endpoint presented a certificate for another hostname and returned no
-  usable capabilities path; status therefore remains `tls_error` and raster
-  acquisition is disabled.
+  read-only GetCapabilities probe. Revalidation on 2026-07-19 still found that
+  `bathy.agentschapmdk.be` presents a certificate for `*.l27powered.eu`.
+  Hostname validation therefore fails with `tls_error`; raster acquisition
+  remains disabled and TLS verification cannot be bypassed.
 - SPW bathymetry of navigable waterways and reservoir lakes: 0.5 m bed
   elevation and XYZ data in mDNG.
 - Port of Antwerp-Bruges periodic soundings: catalog candidate pending a