feat(design-system): Storybook + Button-Atom-Vereinheitlichung + SectionHeader

Storybook (SvelteKit-Framework, Tailwind v4, MSW, Translation-Decorator):
Stories für Atoms/Molecules/Organisms + alle CMS-Blocks.

Button-Atom: 5 .btn-*-Varianten (primary/secondary/tertiary/outline/warning),
class-Merge-Prop, href→<a>, Loading-Spinner neben Label, rounded-md/font-medium.
Alle rohen .btn-*- und Hand-Style-Buttons app-weit aufs Atom migriert.

SectionHeader-Molecule (kicker/number/title/subtitle/action) + Integration in
7 CMS-Blocks (post_overview, organisations, organisations_map, searchable_text,
image_gallery, youtube_video_gallery, files) via neuem section_header-Schema.

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

src/lib/components/ContactCard.stories.ts

@@ -0,0 +1,28 @@
+import type { Meta, StoryObj } from '@storybook/sveltekit';
+import ContactCard from './ContactCard.svelte';
+
+const meta = {
+  title: 'Molecules/ContactCard',
+  component: ContactCard,
+  tags: ['autodocs'],
+} satisfies Meta<typeof ContactCard>;
+
+export default meta;
+type Story = StoryObj<typeof meta>;
+
+export const Standard: Story = {
+  args: {
+    contact: {
+      name: 'Maria Müller',
+      role: 'Sprecherin',
+      email: 'maria@example.org',
+      phone: '01234 567890',
+      note: 'Erreichbar Mo–Fr',
+      organisations: [{ name: 'BI Steigerwald' }],
+    },
+  },
+};
+
+export const Minimal: Story = {
+  args: { contact: { name: 'Hans Weber', role: 'Presse', email: 'presse@example.org' } },
+};