Add documentation for all PDF tools

docs/tools/mobi-to-pdf.md

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+---
+title: MOBI to PDF
+description: Convert MOBI ebook files to PDF directly in your browser. Free, private, no file uploads.
+---
+
+# MOBI to PDF
+
+Convert Amazon Kindle MOBI ebooks into PDF documents. MOBI files are tied to Kindle devices and apps, making them difficult to read elsewhere. Converting to PDF gives you a portable version you can open on any device or print.
+
+## Supported Formats
+
+| Format | Extension | Notes                            |
+| :----- | :-------- | :------------------------------- |
+| MOBI   | `.mobi`   | Kindle ebook format (Mobipocket) |
+
+## How It Works
+
+1. Click the upload area or drag and drop one or more MOBI files.
+2. Review the file list. Remove unwanted files with the trash icon, or use **Add More Files** to include additional ebooks.
+3. Click **Convert to PDF**. The PyMuPDF engine parses the MOBI structure and renders each page as PDF content.
+4. A single file downloads as a PDF. When converting multiple files, you get a ZIP archive named `mobi-converted.zip`.
+
+## Options
+
+No additional settings are needed. The conversion preserves the text content, formatting, and embedded images from the original MOBI file.
+
+## Use Cases
+
+- Reading Kindle-purchased content on a non-Kindle e-reader that only supports PDF
+- Printing chapters from an ebook for offline study or annotation
+- Archiving your personal ebook library in a universal format
+- Sharing excerpts with someone who does not have the Kindle app installed
+
+## Tips
+
+- DRM-protected MOBI files cannot be converted. The tool works with DRM-free MOBI files only.
+- Large ebooks with many embedded images may take a few seconds longer to process since everything happens in the browser.
+
+## Related Tools
+
+- [EPUB to PDF](./epub-to-pdf)
+- [FB2 to PDF](./fb2-to-pdf)
+- [CBZ to PDF](./cbz-to-pdf)