chore: consolidate all persistent data into ./data folder

- Update docker-compose.yml to mount Caddyfile from ./data
- Remove Dockerfile directory creation - handled by init-data.sh
- Add init-data.sh script to initialize ./data with all required files
- Add DATA_DEPLOYMENT.md documentation for deployment workflow
- Update .gitignore to exclude ./data folder
- All persistent data (app, config, database, uploads) now centralized in ./data

DATA_DEPLOYMENT.md

@@ -0,0 +1,75 @@
+# Data Folder Deployment Guide
+
+## Overview
+
+The `./data` folder is the **persistent data storage** for the DigiServer deployment. It is **NOT committed to the repository** but contains all necessary files copied from the repo during deployment.
+
+## Structure
+
+```
+data/
+├── app/                  # Complete application code (copied from ./app)
+├── Caddyfile            # Reverse proxy configuration (copied from root)
+├── instance/            # Flask instance folder (database, configs)
+├── uploads/             # User file uploads
+├── caddy-data/          # Caddy SSL certificates and cache
+└── caddy-config/        # Caddy configuration data
+```
+
+## Deployment Process
+
+### Step 1: Initialize Data Folder
+
+Run this script to copy all necessary files from the repository to `./data`:
+
+```bash
+./init-data.sh
+```
+
+This will:
+- Create the `./data` directory structure
+- Copy `./app` folder to `./data/app`
+- Copy `Caddyfile` to `./data/Caddyfile`
+- Set proper permissions for all files and folders
+
+### Step 2: Start Docker Containers
+
+```bash
+docker-compose up -d --build
+```
+
+### Step 3: Run Migrations (First Time Only)
+
+```bash
+sudo bash deploy.sh
+```
+
+## Important Notes
+
+- **./data is NOT in git**: The `./data` folder is listed in `.gitignore` and will not be committed
+- **All persistent data here**: Database files, uploads, certificates, and configurations are stored in `./data`
+- **Easy backups**: To backup the entire deployment, backup the `./data` folder
+- **Easy troubleshooting**: Check the `./data` folder to verify all required files are present
+- **Updates**: When you pull new changes, run `./init-data.sh` to update app files in `./data`
+
+## Deployment Checklist
+
+✓ All volumes in docker-compose.yml point to `./data`
+✓ `./data` folder contains: app/, Caddyfile, instance/, uploads/, caddy-data/, caddy-config/
+✓ Files are copied from repository to `./data` via init-data.sh
+✓ Permissions are correctly set for Docker container user
+
+## Verification
+
+Before starting:
+```bash
+ls -la data/
+# Should show: app/, Caddyfile, instance/, uploads/, caddy-data/, caddy-config/
+```
+
+After deployment check data folder for:
+```bash
+data/instance/*.db           # Database files
+data/uploads/                # User uploads
+data/caddy-data/*.pem        # SSL certificates
+```