diff --git a/db/migrations/001_initial.sql b/db/migrations/001_initial.sql
new file mode 100644
index 0000000..a077d40
--- /dev/null
+++ b/db/migrations/001_initial.sql
@@ -0,0 +1,163 @@
+-- SeCu Database Schema
+-- Version: 1.0.0
+
+-- Enable UUID extension
+CREATE EXTENSION IF NOT EXISTS "uuid-ossp";
+
+-- Organizations
+CREATE TABLE IF NOT EXISTS organizations (
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    name VARCHAR(255) NOT NULL,
+    slug VARCHAR(100) NOT NULL UNIQUE,
+    settings JSONB DEFAULT '{}',
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
+);
+
+-- Users
+CREATE TABLE IF NOT EXISTS users (
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    org_id UUID NOT NULL REFERENCES organizations(id) ON DELETE CASCADE,
+    email VARCHAR(255) NOT NULL,
+    password_hash VARCHAR(255) NOT NULL,
+    role VARCHAR(20) NOT NULL CHECK (role IN ('chef', 'disponent', 'mitarbeiter')),
+    first_name VARCHAR(100) NOT NULL,
+    last_name VARCHAR(100) NOT NULL,
+    phone VARCHAR(50),
+    avatar_url TEXT,
+    created_by UUID REFERENCES users(id),
+    managed_by UUID REFERENCES users(id),
+    active BOOLEAN DEFAULT true,
+    last_login TIMESTAMP WITH TIME ZONE,
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    UNIQUE(org_id, email)
+);
+
+-- Refresh Tokens
+CREATE TABLE IF NOT EXISTS refresh_tokens (
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    token_hash VARCHAR(255) NOT NULL,
+    expires_at TIMESTAMP WITH TIME ZONE NOT NULL,
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
+);
+
+-- Orders (Aufträge)
+CREATE TABLE IF NOT EXISTS orders (
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    org_id UUID NOT NULL REFERENCES organizations(id) ON DELETE CASCADE,
+    number SERIAL,
+    title VARCHAR(255) NOT NULL,
+    description TEXT,
+    location VARCHAR(255),
+    address TEXT,
+    client_name VARCHAR(255),
+    client_contact VARCHAR(255),
+    status VARCHAR(20) NOT NULL DEFAULT 'draft' CHECK (status IN ('draft', 'published', 'in_progress', 'completed', 'cancelled')),
+    start_time TIMESTAMP WITH TIME ZONE,
+    end_time TIMESTAMP WITH TIME ZONE,
+    required_staff INTEGER DEFAULT 1,
+    special_instructions TEXT,
+    created_by UUID REFERENCES users(id),
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
+);
+
+-- Order Assignments (Mitarbeiter-Zuweisung)
+CREATE TABLE IF NOT EXISTS order_assignments (
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    order_id UUID NOT NULL REFERENCES orders(id) ON DELETE CASCADE,
+    user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    status VARCHAR(20) NOT NULL DEFAULT 'pending' CHECK (status IN ('pending', 'confirmed', 'declined', 'completed')),
+    note TEXT,
+    confirmed_at TIMESTAMP WITH TIME ZONE,
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    UNIQUE(order_id, user_id)
+);
+
+-- Availability (Verfügbarkeit)
+CREATE TABLE IF NOT EXISTS availability (
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    date DATE NOT NULL,
+    available BOOLEAN NOT NULL DEFAULT true,
+    time_from TIME,
+    time_to TIME,
+    note TEXT,
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    UNIQUE(user_id, date)
+);
+
+-- Timesheets (Stundenzettel)
+CREATE TABLE IF NOT EXISTS timesheets (
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    order_id UUID REFERENCES orders(id) ON DELETE SET NULL,
+    work_date DATE NOT NULL,
+    start_time TIME,
+    end_time TIME,
+    hours_worked DECIMAL(5,2),
+    photo_url TEXT,
+    status VARCHAR(20) NOT NULL DEFAULT 'pending' CHECK (status IN ('pending', 'approved', 'rejected')),
+    approved_by UUID REFERENCES users(id),
+    rejection_reason TEXT,
+    approved_at TIMESTAMP WITH TIME ZONE,
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
+);
+
+-- Modules (für modulares System)
+CREATE TABLE IF NOT EXISTS modules (
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    name VARCHAR(100) NOT NULL UNIQUE,
+    display_name VARCHAR(255) NOT NULL,
+    description TEXT,
+    is_core BOOLEAN DEFAULT false,
+    default_config JSONB DEFAULT '{}',
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW()
+);
+
+-- Organization Modules (welche Module aktiviert)
+CREATE TABLE IF NOT EXISTS organization_modules (
+    id UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    org_id UUID NOT NULL REFERENCES organizations(id) ON DELETE CASCADE,
+    module_id UUID NOT NULL REFERENCES modules(id) ON DELETE CASCADE,
+    enabled BOOLEAN DEFAULT true,
+    config JSONB DEFAULT '{}',
+    enabled_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    UNIQUE(org_id, module_id)
+);
+
+-- Indexes for performance
+CREATE INDEX IF NOT EXISTS idx_users_org_id ON users(org_id);
+CREATE INDEX IF NOT EXISTS idx_users_email ON users(email);
+CREATE INDEX IF NOT EXISTS idx_users_role ON users(role);
+CREATE INDEX IF NOT EXISTS idx_users_managed_by ON users(managed_by);
+CREATE INDEX IF NOT EXISTS idx_orders_org_id ON orders(org_id);
+CREATE INDEX IF NOT EXISTS idx_orders_status ON orders(status);
+CREATE INDEX IF NOT EXISTS idx_orders_start_time ON orders(start_time);
+CREATE INDEX IF NOT EXISTS idx_order_assignments_order_id ON order_assignments(order_id);
+CREATE INDEX IF NOT EXISTS idx_order_assignments_user_id ON order_assignments(user_id);
+CREATE INDEX IF NOT EXISTS idx_availability_user_id ON availability(user_id);
+CREATE INDEX IF NOT EXISTS idx_availability_date ON availability(date);
+CREATE INDEX IF NOT EXISTS idx_timesheets_user_id ON timesheets(user_id);
+CREATE INDEX IF NOT EXISTS idx_timesheets_work_date ON timesheets(work_date);
+CREATE INDEX IF NOT EXISTS idx_timesheets_status ON timesheets(status);
+CREATE INDEX IF NOT EXISTS idx_refresh_tokens_user_id ON refresh_tokens(user_id);
+
+-- Seed data: Core modules
+INSERT INTO modules (name, display_name, description, is_core) VALUES
+    ('core', 'Kernfunktionen', 'Authentifizierung und Benutzerverwaltung', true),
+    ('orders', 'Auftragsverwaltung', 'Erstellen und Verwalten von Aufträgen', true),
+    ('availability', 'Verfügbarkeit', 'Mitarbeiter-Verfügbarkeitsplanung', false),
+    ('timesheets', 'Stundenzettel', 'Zeiterfassung und Stundenzettel-Upload', false),
+    ('developer', 'Entwickler-Panel', 'Fernverwaltung und Modul-Konfiguration', false)
+ON CONFLICT (name) DO NOTHING;
+
+-- Create a default demo organization
+INSERT INTO organizations (name, slug) VALUES
+    ('Demo Organisation', 'demo')
+ON CONFLICT (slug) DO NOTHING;