feat(parcel-sync): native PostGIS geometry support for QGIS

- Remove postgresqlExtensions/postgis from Prisma schema (PostGIS not yet installed)
- Add prisma/postgis-setup.sql: trigger auto-converts GeoJSON→native geometry,
  GiST spatial index, QGIS-friendly views (gis_terenuri, gis_cladiri, etc.)
- Add POST /api/eterra/setup-postgis endpoint (idempotent, runs all SQL setup)
- Add safety-net raw SQL in sync-service: backfills geom after upsert phase
- Add QGIS/PostGIS setup card in layer catalog UI with connection info
- Schema comment documents the trigger-managed 'geom' column approach

prisma/schema.prisma

@@ -1,12 +1,10 @@
 generator client {
-  provider        = "prisma-client-js"
-  previewFeatures = ["postgresqlExtensions"]
+  provider = "prisma-client-js"
 }
 
 datasource db {
-  provider   = "postgresql"
-  url        = env("DATABASE_URL")
-  extensions = [postgis]
+  provider = "postgresql"
+  url      = env("DATABASE_URL")
 }
 
 model KeyValueStore {
@@ -24,20 +22,22 @@ model KeyValueStore {
 // ─── GIS: eTerra ParcelSync ────────────────────────────────────────
 
 model GisFeature {
-  id           String   @id @default(uuid())
-  layerId      String   // e.g. TERENURI_ACTIVE, CLADIRI_ACTIVE
+  id           String                          @id @default(uuid())
+  layerId      String                          // e.g. TERENURI_ACTIVE, CLADIRI_ACTIVE
   siruta       String
-  objectId     Int      // eTerra OBJECTID (unique per layer)
+  objectId     Int                             // eTerra OBJECTID (unique per layer)
   inspireId    String?
-  cadastralRef String?  // NATIONAL_CADASTRAL_REFERENCE
+  cadastralRef String?                         // NATIONAL_CADASTRAL_REFERENCE
   areaValue    Float?
-  isActive     Boolean  @default(true)
-  attributes   Json     // all raw eTerra attributes
-  geometry     Json?    // GeoJSON geometry (Polygon/MultiPolygon)
+  isActive     Boolean                         @default(true)
+  attributes   Json                            // all raw eTerra attributes
+  geometry     Json?                           // GeoJSON geometry (Polygon/MultiPolygon)
+  // NOTE: native PostGIS column 'geom' is managed via SQL trigger (see prisma/postgis-setup.sql)
+  //       Prisma doesn't need to know about it — trigger auto-populates from geometry JSON
   syncRunId    String?
-  projectId    String?  // link to project tag
-  createdAt    DateTime @default(now())
-  updatedAt    DateTime @updatedAt
+  projectId    String?                         // link to project tag
+  createdAt    DateTime                        @default(now())
+  updatedAt    DateTime                        @updatedAt
 
   syncRun GisSyncRun? @relation(fields: [syncRunId], references: [id])