docs: update README and Copilot instructions for new DB init workflow

Replace placeholder clone URL with actual repo URL:
https://github.com/RobbStarkAustria/infoscreen_2025.git
Add first-run step to initialize the database using the one-shot script:
python server/initialize_database.py
Mention initialize_database.py in project structure
Add a one-shot DB init command to the “Database Management” section
Update Copilot instructions:
Prefer initialize_database.py for local dev (migrations + defaults + academic periods)
Note legacy init scripts were removed; use Alembic + initialize_database.py going forward
No runtime/code changes; documentation only

README.md

@@ -82,7 +82,7 @@ A comprehensive multi-service digital signage solution for educational instituti
 
 1. **Clone the repository**
    ```bash
-   git clone <repository-url>
+   git clone https://github.com/RobbStarkAustria/infoscreen_2025.git
    cd infoscreen_2025
    ```
 
@@ -98,7 +98,13 @@ A comprehensive multi-service digital signage solution for educational instituti
    # or: docker compose up -d --build
    ```
 
-4. **Access the services**
+4. **Initialize the database (first run only)**
+   ```bash
+   # One-shot: runs all Alembic migrations, creates default admin/group, and seeds academic periods
+   python server/initialize_database.py
+   ```
+
+5. **Access the services**
    - Dashboard: http://localhost:5173
    - API: http://localhost:8000
    - Database: localhost:3306
@@ -177,6 +183,7 @@ infoscreen_2025/
 │   ├── routes/               # API endpoints
 │   ├── alembic/              # Database migrations
 │   ├── media/                # File storage
+│   ├── initialize_database.py # All-in-one DB initialization (dev)
 │   └── worker.py             # Background jobs
 ├── listener/                 # MQTT listener service
 ├── scheduler/                # Event scheduling service
@@ -213,6 +220,9 @@ make fix-perms     # Fix file permissions
 ### Database Management
 
 ```bash
+# One-shot initialization (schema + defaults + academic periods)
+python server/initialize_database.py
+
 # Access database directly
 docker exec -it infoscreen-db mysql -u${DB_USER} -p${DB_PASSWORD} ${DB_NAME}