Restructure docs into manual/development and add implementation docs (#94)

## Summary by Sourcery

Restructure documentation into separate manual and development sections,
introduce detailed internal implementation docs for auth/Java/mod
loaders, and update site navigation, landing page links, and MDX tooling
(Mermaid, card styling) to match the new structure and tech stack.

Enhancements:
- Enable Mermaid rendering support in the docs app and add a reusable
Mermaid React component.
- Refine Docs page rendering by customizing Card styling and removing
redundant in-page titles/descriptions rendered by the layout.
- Align docs source configuration and routing comments with the new
manual-based default paths.

Documentation:
- Split user-facing docs under a new manual section and move contributor
content into a dedicated development section for both English and
Chinese.
- Add comprehensive internal implementation documentation covering
authentication, Java management, mod loader/version merging, event bus,
and architecture patterns in both English and Chinese.
- Update existing feature docs (mod loaders, Java, authentication) and
getting-started/troubleshooting pages to be more conceptual, pointing to
implementation docs for technical details.
- Refresh architecture docs to reflect the React/Zustand frontend stack
and add Mermaid-based architecture diagrams.
- Adjust navigation labels, home-page CTAs, and doc links to target the
new manual/development structure and routes.

---------

Co-authored-by: 简律纯 <i@jyunko.cn>

1 files changed, 95 insertions, 0 deletions

diff --git a/packages/docs/content/en/manual/index.mdx b/packages/docs/content/en/manual/index.mdx
new file mode 100644
index 0000000..9dee19f
--- /dev/null
+++ b/packages/docs/content/en/manual/index.mdx
@@ -0,0 +1,95 @@
+---
+title: Welcome to DropOut
+description: Modern, reproducible, and developer-grade Minecraft launcher
+---
+
+# Welcome to DropOut
+
+DropOut is a modern Minecraft launcher built with Tauri v2 and Rust, designed for players who value control, transparency, and long-term stability.
+
+<div style={{ textAlign: 'center', margin: '2rem 0' }}>
+  <img src="/image.png" alt="DropOut Launcher" style={{ maxWidth: '700px', borderRadius: '8px' }} />
+</div>
+
+## Why DropOut?
+
+Most Minecraft launchers focus on getting you into the game. DropOut focuses on keeping your game **stable**, **debuggable**, and **reproducible**.
+
+- Your instance worked yesterday but broke today? → **DropOut makes it traceable.**
+- Sharing a modpack means zipping gigabytes? → **DropOut shares exact dependency manifests.**
+- Java, loader, mods, configs drift out of sync? → **DropOut locks them together.**
+
+This launcher is built for players who value control, transparency, and long-term stability.
+
+## Quick Links
+
+<Cards>
+  <Card 
+    title="Getting Started" 
+    href="getting-started"
+    description="Install and set up DropOut in minutes"
+  />
+  <Card 
+    title="Features" 
+    href="features"
+    description="Explore all the capabilities of DropOut"
+  />
+  <Card 
+    title="Architecture" 
+    href="architecture"
+    description="Learn about the technical design"
+  />
+  <Card 
+    title="Development" 
+    href="development"
+    description="Build and contribute to DropOut"
+  />
+</Cards>
+
+## Key Features
+
+### High Performance
+Built with Rust and Tauri for minimal resource usage and fast startup times.
+
+### Modern UI
+Clean, distraction-free interface with Svelte 5, Tailwind CSS 4, and particle effects.
+
+### Secure Authentication
+Microsoft OAuth 2.0 with device code flow and offline authentication support.
+
+### Mod Loader Support
+Built-in installation for Fabric and Forge with automatic version management.
+
+### Java Management
+Automatic detection of installed Java versions and integrated downloader for Adoptium JDK/JRE.
+
+### Instance System
+Isolated game environments with independent configurations, mods, and saves.
+
+### AI Assistant
+Built-in AI helper for troubleshooting, configuration, and guidance.
+
+### Fast Downloads
+Concurrent asset and library downloads with resume support and progress tracking.
+
+## Technology Stack
+
+- **Backend**: Rust with Tauri v2
+- **Frontend**: Svelte 5 with runes
+- **Styling**: Tailwind CSS 4
+- **Build Tool**: Vite with Rolldown
+- **Documentation**: Fumadocs with React Router
+
+## Community
+
+- **GitHub**: [HydroRoll-Team/DropOut](https://github.com/HydroRoll-Team/DropOut)
+- **Issues**: [Report bugs](https://github.com/HydroRoll-Team/DropOut/issues)
+- **Roadmap**: [View development roadmap](https://roadmap.sh/r/minecraft-launcher-dev)
+
+## License
+
+DropOut is open source software licensed under the MIT License.
+
+---
+
+Ready to get started? Check out the [Getting Started Guide](getting-started)!