feat: Initial Docusaurus setup with Stock Market Professional docs

- Set up Docusaurus with pnpm and TypeScript
- Structured docs for multi-application portfolio
- Added Stock Market Professional documentation:
  - Architecture & system design
  - Data monitoring module
  - Technical analysis engine
  - Signal generation with constraints (max 3/day, 30min hold)
- Added platform architecture overview
- Added getting started guide
- Added Gitea Actions CI/CD pipeline (build + artifact)

docs/guides/getting-started.md

@@ -0,0 +1,79 @@
+---
+sidebar_position: 1
+---
+
+# Getting Started
+
+## Prerequisites
+
+- Node.js 18+
+- pnpm (`npm install -g pnpm`)
+- Git access to gitea.lego-cloud.eu
+
+## Development
+
+### Clone the repository
+
+```bash
+git clone ssh://git@gitea.lego-cloud.eu:30009/skic-v1-playground/documentation.git
+cd documentation
+```
+
+### Install dependencies
+
+```bash
+pnpm install
+```
+
+### Start development server
+
+```bash
+pnpm start
+```
+
+The site will be available at `http://localhost:3000`.
+
+### Build for production
+
+```bash
+pnpm build
+```
+
+### Serve production build locally
+
+```bash
+pnpm serve
+```
+
+## Adding Documentation
+
+### New Application
+
+1. Create a directory under `docs/applications/your-app-name/`
+2. Add an `index.md` with frontmatter
+3. Create subdirectories for each module
+4. Update `sidebars.ts` to include the new section
+
+### New Guide
+
+1. Create a markdown file under `docs/guides/`
+2. Add frontmatter with `sidebar_position`
+3. Update `sidebars.ts` if needed
+
+## Project Structure
+
+```
+documentation/
+├── docs/                    # Documentation content
+│   ├── intro/              # Welcome & overview
+│   ├── applications/       # Per-application docs
+│   │   └── stock-market-professional/
+│   ├── architecture/       # Platform-wide architecture
+│   └── guides/             # How-to guides
+├── blog/                   # Changelog / updates
+├── src/                    # Custom components & CSS
+├── static/                 # Static assets
+├── docusaurus.config.ts    # Site configuration
+├── sidebars.ts             # Sidebar structure
+└── package.json            # Dependencies
+```