docs: comprehensive documentation overhaul

Add complete documentation structure:
- Frontend architecture documentation
- Database schema documentation
- Deployment guides (Docker, Traefik, Authentik, Environment)
- Development guides (Setup, Testing, Contributing, Quality Gates)
- Deployment architecture documentation
- Updated docs README with complete navigation

All new features and APIs are now documented.
Quality gates: docs only, no code changes

docs/features/tool-types.md

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+# Tool Types
+
+## Overview
+
+Tool types define development tools that can be spawned for projects. Headquarter includes built-in types and supports creating custom tool types with Docker Compose templates.
+
+## How to Use
+
+### Built-in Tool Types
+
+Headquarter includes these built-in tool types:
+
+#### VS Code Server
+- **Image**: `lscr.io/linuxserver/code-server:latest`
+- **Purpose**: Full VS Code in the browser
+- **Features**: Extensions, terminal, debugging
+- **Access**: Port 8443
+
+#### Jupyter Notebook
+- **Image**: `jupyter/scipy-notebook:latest`
+- **Purpose**: Interactive Python development
+- **Features**: Notebooks, data visualization
+- **Access**: Port 8888
+
+### Managing Tool Types
+
+#### Viewing Tool Types
+
+1. Navigate to **Settings** → **Tool Types**
+2. See a list of all tool types
+3. Built-in types are marked with a badge
+
+#### Creating Custom Tool Types
+
+1. Click **"New Tool Type"**
+2. Fill in the form:
+   - **Name**: Unique identifier (e.g., `my-custom-tool`)
+   - **Display Name**: Human-readable name
+   - **Description**: What this tool does
+   - **Compose Template**: Docker Compose YAML
+3. Click **"Create"**
+
+#### Compose Template Format
+
+The compose template uses Docker Compose syntax with template variables:
+
+```yaml
+version: "3.8"
+services:
+  my-tool:
+    image: my-image:latest
+    container_name: {{TOOL_NAME}}
+    environment:
+      - VARIABLE=value
+    volumes:
+      - {{REPO_PATH}}:/workspace
+    ports:
+      - "8080:8080"
+```
+
+**Required Variables:**
+- `{{TOOL_NAME}}` - Unique name for the container
+- `{{REPO_PATH}}` - Path to the repository
+
+#### Validating Templates
+
+The system validates templates:
+- Must be valid YAML
+- Must contain a `services` section
+- Must use all required variables
+- Invalid templates will be rejected
+
+#### Editing Tool Types
+
+1. Find the tool type in the list
+2. Click **"Edit"**
+3. Update fields
+4. Click **"Save"**
+
+**Note:** Built-in tool types cannot be modified or deleted.
+
+#### Deleting Tool Types
+
+1. Find the tool type in the list
+2. Click **"Delete"**
+3. Confirm deletion
+
+**Note:** Built-in tool types cannot be deleted.
+
+## API Reference
+
+### Endpoints
+
+- `GET /tool-types` - List tool types
+- `POST /tool-types` - Create tool type
+- `GET /tool-types/{id}` - Get tool type details
+- `PUT /tool-types/{id}` - Update tool type
+- `DELETE /tool-types/{id}` - Delete tool type
+
+See [Tool Types API](../api/tool-types.md) for detailed endpoint documentation.
+
+## Related Features
+
+- [Tool Instances](tool-instances.md) - Spawn and manage tool instances