V2 docker support react version2 (#3930)

# Description of Changes

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Please provide a summary of the changes, including:

- What was changed
- Why the change was made
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Closes #(issue_number)
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---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.

---------

Co-authored-by: a <a>

docker/README.md

@@ -0,0 +1,67 @@
+# Docker Setup for Stirling-PDF
+
+This directory contains the organized Docker configurations for the split frontend/backend architecture.
+
+## Directory Structure
+
+```
+docker/
+├── backend/           # Backend Docker files
+│   ├── Dockerfile            # Standard backend
+│   ├── Dockerfile.ultra-lite # Minimal backend
+│   └── Dockerfile.fat        # Full-featured backend
+├── frontend/          # Frontend Docker files
+│   ├── Dockerfile     # React/Vite frontend with nginx
+│   ├── nginx.conf     # Nginx configuration
+│   └── entrypoint.sh  # Dynamic backend URL setup
+├── monolith/          # Single container setup
+│   ├── Dockerfile           # Combined frontend + backend
+│   ├── nginx-monolith.conf  # Nginx config for monolith
+│   └── start-monolith.sh    # Startup script
+└── compose/           # Docker Compose files
+    ├── docker-compose.yml           # Standard setup
+    ├── docker-compose.ultra-lite.yml # Ultra-lite setup
+    ├── docker-compose.fat.yml       # Full-featured setup
+    └── docker-compose.monolith.yml  # Single container setup
+```
+
+## Usage
+
+### Separate Containers (Recommended)
+
+From the project root directory:
+
+```bash
+# Standard version
+docker-compose -f docker/compose/docker-compose.yml up --build
+
+# Ultra-lite version
+docker-compose -f docker/compose/docker-compose.ultra-lite.yml up --build
+
+# Fat version
+docker-compose -f docker/compose/docker-compose.fat.yml up --build
+```
+
+### Single Container (Monolith)
+
+```bash
+# Single container with both frontend and backend
+docker-compose -f docker/compose/docker-compose.monolith.yml up --build
+```
+
+## Access Points
+
+- **Frontend**: http://localhost:3000
+- **Backend API (debugging)**: http://localhost:8080 (TODO: Remove in production)
+- **Backend API (via frontend)**: http://localhost:3000/api/*
+
+## Configuration
+
+- **Backend URL**: Set `BACKEND_URL` environment variable for custom backend locations
+- **Custom Ports**: Modify port mappings in docker-compose files
+- **Memory Limits**: Adjust memory limits per variant (2G ultra-lite, 4G standard, 6G fat)
+
+## Development vs Production
+
+- **Development**: Keep backend port 8080 exposed for debugging
+- **Production**: Remove backend port exposure, use only frontend proxy