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>

.storybook/main.ts

@@ -1,18 +1,11 @@
 import type { StorybookConfig } from '@storybook/angular';
 
 const config: StorybookConfig = {
-  "stories": [
-    "../src/**/*.mdx",
-    "../src/**/*.stories.@(js|jsx|mjs|ts|tsx)"
-  ],
-  "addons": [
-    "@storybook/addon-a11y",
-    "@storybook/addon-docs",
-    "@storybook/addon-onboarding"
-  ],
-  "framework": "@storybook/angular",
+  stories: ['../src/**/*.mdx', '../src/**/*.stories.@(js|jsx|mjs|ts|tsx)'],
+  addons: ['@storybook/addon-a11y', '@storybook/addon-docs', '@storybook/addon-onboarding'],
+  framework: '@storybook/angular',
   // Serve the vendored CIBG package so preview-head.html can <link> its CSS (and its
   // relative font/icon/image url()s resolve) — mirrors index.html for the real app.
-  "staticDirs": ["../public"]
+  staticDirs: ['../public'],
 };
-export default config;
+export default config;