style: format frontend, docs and skills with prettier; add .prettierignore

One-time prettier --write so the new format:check CI gate starts green.
.prettierignore excludes generated (api-client.ts, documentation.json),
vendored (public/cibg-huisstijl), and backend (dotnet format owns it).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docker-compose.yml

@@ -13,7 +13,7 @@ services:
       - api-bin:/src/src/BigRegister.Api/bin
       - api-obj:/src/src/BigRegister.Api/obj
     ports:
-      - "5000:5000"
+      - '5000:5000'
 
   web:
     image: node:24
@@ -24,7 +24,7 @@ services:
       - ./:/app:z
       - web-modules:/app/node_modules
     ports:
-      - "4200:4200"
+      - '4200:4200'
     depends_on:
       - api