refactor(theme): remove custom theme editor and community themes

Remove unused custom theme functionality:
- Delete custom-themes-store.svelte.ts from shared-theme
- Remove ThemeEditor, ColorPicker, ThemeLivePreview components
- Remove CommunityThemeGallery, ThemeCommunityCard components
- Remove ThemeEditorPage, CommunityThemesPage
- Simplify ThemePage to show only built-in themes
- Remove editor and community routes from contacts app
- Update THEMING.md documentation

The built-in theme variants (default, ocean, forest, sunset, etc.)
provide sufficient customization. Custom theme creation was never
fully implemented and added unnecessary complexity.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/contacts/apps/web/src/lib/stores/custom-themes.svelte.ts

@@ -1,15 +0,0 @@
-/**
- * Custom Themes Store - Manages user's custom themes and community themes
- */
-
-import { createCustomThemesStore } from '@manacore/shared-theme';
-import { authStore } from './auth.svelte';
-
-// Auth URL for theme API calls
-const MANA_AUTH_URL = 'http://localhost:3001';
-
-// Create the custom themes store
-export const customThemesStore = createCustomThemesStore({
-	authUrl: MANA_AUTH_URL,
-	getAccessToken: () => authStore.getAccessToken(),
-});

apps/contacts/apps/web/src/routes/(app)/themes/+page.svelte

@@ -2,7 +2,6 @@
 	import { goto } from '$app/navigation';
 	import { ThemePage } from '@manacore/shared-theme-ui';
 	import { theme } from '$lib/stores/theme';
-	import { customThemesStore } from '$lib/stores/custom-themes.svelte';
 </script>
 
 <svelte:head>
@@ -17,9 +16,4 @@
 	onModeChange={(m) => theme.setMode(m)}
 	showBackButton={true}
 	onBack={() => goto('/')}
-	showCustomThemes={true}
-	{customThemesStore}
-	onCreateTheme={() => goto('/themes/editor')}
-	onEditTheme={(t) => goto(`/themes/editor?id=${t.id}`)}
-	onCommunityThemes={() => goto('/themes/community')}
 />

apps/contacts/apps/web/src/routes/(app)/themes/community/+page.svelte

@@ -1,29 +0,0 @@
-<script lang="ts">
-	import { goto } from '$app/navigation';
-	import { CommunityThemesPage } from '@manacore/shared-theme-ui';
-	import { customThemesStore } from '$lib/stores/custom-themes.svelte';
-	import { theme } from '$lib/stores/theme';
-
-	// Get effective mode from theme store
-	let effectiveMode = $derived(
-		theme.mode === 'system'
-			? typeof window !== 'undefined' && window.matchMedia('(prefers-color-scheme: dark)').matches
-				? 'dark'
-				: 'light'
-			: theme.mode
-	) as 'light' | 'dark';
-</script>
-
-<svelte:head>
-	<title>Community Themes | Contacts</title>
-</svelte:head>
-
-<CommunityThemesPage
-	store={customThemesStore}
-	{effectiveMode}
-	onBack={() => goto('/themes')}
-	onSelectTheme={(t) => {
-		// Could open a detail modal here
-		console.log('Selected theme:', t);
-	}}
-/>

apps/contacts/apps/web/src/routes/(app)/themes/editor/+page.svelte

@@ -1,75 +0,0 @@
-<script lang="ts">
-	import { goto } from '$app/navigation';
-	import { page } from '$app/stores';
-	import { ThemeEditorPage } from '@manacore/shared-theme-ui';
-	import { customThemesStore } from '$lib/stores/custom-themes.svelte';
-	import { theme } from '$lib/stores/theme';
-	import { onMount } from 'svelte';
-	import type { CustomTheme } from '@manacore/shared-theme';
-
-	// Get theme ID from URL if editing
-	let themeId = $derived($page.url.searchParams.get('id'));
-	let editingTheme = $state<CustomTheme | undefined>(undefined);
-
-	// Load theme data if editing
-	onMount(async () => {
-		if (themeId) {
-			await customThemesStore.loadCustomThemes();
-			editingTheme = customThemesStore.customThemes.find((t) => t.id === themeId);
-		}
-	});
-
-	// Get effective mode from theme store
-	let effectiveMode = $derived(
-		theme.mode === 'system'
-			? typeof window !== 'undefined' && window.matchMedia('(prefers-color-scheme: dark)').matches
-				? 'dark'
-				: 'light'
-			: theme.mode
-	) as 'light' | 'dark';
-
-	async function handleSave(themeData: {
-		name: string;
-		description?: string;
-		emoji: string;
-		lightColors: any;
-		darkColors: any;
-	}) {
-		if (themeId && editingTheme) {
-			await customThemesStore.updateTheme(themeId, themeData);
-		} else {
-			await customThemesStore.createTheme(themeData);
-		}
-		goto('/themes');
-	}
-
-	async function handlePublish(themeData: {
-		name: string;
-		description?: string;
-		emoji: string;
-		lightColors: any;
-		darkColors: any;
-		tags?: string[];
-	}) {
-		let theme: CustomTheme;
-		if (themeId && editingTheme) {
-			theme = await customThemesStore.updateTheme(themeId, themeData);
-		} else {
-			theme = await customThemesStore.createTheme(themeData);
-		}
-		await customThemesStore.publishTheme(theme.id, { tags: themeData.tags });
-		goto('/themes');
-	}
-</script>
-
-<svelte:head>
-	<title>{themeId ? 'Theme bearbeiten' : 'Neues Theme'} | Contacts</title>
-</svelte:head>
-
-<ThemeEditorPage
-	{effectiveMode}
-	existingTheme={editingTheme}
-	onBack={() => goto('/themes')}
-	onSave={handleSave}
-	onPublish={handlePublish}
-/>