feat: add monorepo configuration and shared packages structure

Root-level setup:
- package.json with Turborepo scripts
- pnpm-workspace.yaml for workspace management
- turbo.json for build pipeline
- Common config files (.nvmrc, .prettierrc, .editorconfig)

Shared packages (packages/):
- @manacore/shared-types - Common TypeScript types
- @manacore/shared-supabase - Unified Supabase client
- @manacore/shared-utils - Date, string, async utilities
- @manacore/shared-ui - React Native UI components (placeholder)

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

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

packages/shared-utils/package.json

@@ -0,0 +1,21 @@
+{
+  "name": "@manacore/shared-utils",
+  "version": "0.1.0",
+  "private": true,
+  "description": "Shared utility functions for Manacore monorepo",
+  "main": "./src/index.ts",
+  "types": "./src/index.ts",
+  "exports": {
+    ".": "./src/index.ts"
+  },
+  "scripts": {
+    "type-check": "tsc --noEmit",
+    "clean": "rm -rf dist"
+  },
+  "dependencies": {
+    "date-fns": "^4.1.0"
+  },
+  "devDependencies": {
+    "typescript": "^5.9.2"
+  }
+}

packages/shared-utils/src/async.ts

@@ -0,0 +1,71 @@
+/**
+ * Async utility functions
+ */
+
+/**
+ * Sleep for a specified number of milliseconds
+ */
+export function sleep(ms: number): Promise<void> {
+  return new Promise((resolve) => setTimeout(resolve, ms));
+}
+
+/**
+ * Retry a function with exponential backoff
+ */
+export async function retry<T>(
+  fn: () => Promise<T>,
+  options: {
+    maxAttempts?: number;
+    initialDelay?: number;
+    maxDelay?: number;
+    backoffMultiplier?: number;
+  } = {}
+): Promise<T> {
+  const {
+    maxAttempts = 3,
+    initialDelay = 1000,
+    maxDelay = 10000,
+    backoffMultiplier = 2,
+  } = options;
+
+  let lastError: Error | undefined;
+  let delay = initialDelay;
+
+  for (let attempt = 1; attempt <= maxAttempts; attempt++) {
+    try {
+      return await fn();
+    } catch (error) {
+      lastError = error as Error;
+
+      if (attempt === maxAttempts) {
+        break;
+      }
+
+      await sleep(delay);
+      delay = Math.min(delay * backoffMultiplier, maxDelay);
+    }
+  }
+
+  throw lastError;
+}
+
+/**
+ * Debounce a function
+ */
+export function debounce<T extends (...args: any[]) => any>(
+  fn: T,
+  delay: number
+): (...args: Parameters<T>) => void {
+  let timeoutId: NodeJS.Timeout | null = null;
+
+  return (...args: Parameters<T>) => {
+    if (timeoutId) {
+      clearTimeout(timeoutId);
+    }
+
+    timeoutId = setTimeout(() => {
+      fn(...args);
+      timeoutId = null;
+    }, delay);
+  };
+}

packages/shared-utils/src/date.ts

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+/**
+ * Date utility functions
+ */
+
+import { format, formatDistanceToNow, parseISO } from 'date-fns';
+import { de, enUS } from 'date-fns/locale';
+
+const locales = {
+  de,
+  en: enUS,
+};
+
+type LocaleKey = keyof typeof locales;
+
+/**
+ * Format a date string to a readable format
+ */
+export function formatDate(
+  date: string | Date,
+  formatStr: string = 'PPP',
+  locale: LocaleKey = 'de'
+): string {
+  const dateObj = typeof date === 'string' ? parseISO(date) : date;
+  return format(dateObj, formatStr, { locale: locales[locale] });
+}
+
+/**
+ * Get relative time from now (e.g., "2 hours ago")
+ */
+export function formatRelativeTime(date: string | Date, locale: LocaleKey = 'de'): string {
+  const dateObj = typeof date === 'string' ? parseISO(date) : date;
+  return formatDistanceToNow(dateObj, {
+    addSuffix: true,
+    locale: locales[locale],
+  });
+}
+
+/**
+ * Format a date for API requests (ISO string)
+ */
+export function toISOString(date: Date): string {
+  return date.toISOString();
+}

packages/shared-utils/src/index.ts

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+/**
+ * Shared utility functions for Manacore monorepo
+ */
+
+// Date utilities
+export * from './date';
+
+// String utilities
+export * from './string';
+
+// Async utilities
+export * from './async';

packages/shared-utils/src/string.ts

@@ -0,0 +1,43 @@
+/**
+ * String utility functions
+ */
+
+/**
+ * Truncate a string to a maximum length with ellipsis
+ */
+export function truncate(str: string, maxLength: number): string {
+  if (str.length <= maxLength) return str;
+  return str.slice(0, maxLength - 3) + '...';
+}
+
+/**
+ * Capitalize the first letter of a string
+ */
+export function capitalize(str: string): string {
+  if (!str) return str;
+  return str.charAt(0).toUpperCase() + str.slice(1);
+}
+
+/**
+ * Generate a random string ID
+ */
+export function generateId(length: number = 8): string {
+  const chars = 'abcdefghijklmnopqrstuvwxyz0123456789';
+  let result = '';
+  for (let i = 0; i < length; i++) {
+    result += chars.charAt(Math.floor(Math.random() * chars.length));
+  }
+  return result;
+}
+
+/**
+ * Slugify a string for URLs
+ */
+export function slugify(str: string): string {
+  return str
+    .toLowerCase()
+    .trim()
+    .replace(/[^\w\s-]/g, '')
+    .replace(/[\s_-]+/g, '-')
+    .replace(/^-+|-+$/g, '');
+}

packages/shared-utils/tsconfig.json

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+{
+  "compilerOptions": {
+    "target": "ES2020",
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "lib": ["ES2020"],
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "forceConsistentCasingInFileNames": true,
+    "declaration": true,
+    "declarationMap": true,
+    "outDir": "./dist"
+  },
+  "include": ["src/**/*"],
+  "exclude": ["node_modules", "dist"]
+}