Add documentation for all PDF tools

docs/tools/odt-to-pdf.md

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+---
+title: ODT to PDF
+description: Convert OpenDocument Text (ODT) files to PDF format in your browser using a LibreOffice-powered engine.
+---
+
+# ODT to PDF
+
+Convert OpenDocument Text files to PDF. ODT is the native format of LibreOffice Writer, Apache OpenOffice, and other open-source word processors. This tool uses a browser-based LibreOffice engine to produce accurate conversions that preserve formatting, tables, images, and styles.
+
+## Supported Formats
+
+| Format            | Extensions |
+| :---------------- | :--------- |
+| OpenDocument Text | `.odt`     |
+
+## How It Works
+
+1. Click the upload area or drag and drop one or more ODT files.
+2. Review the file list. Add more files or remove unwanted ones.
+3. Click **Convert to PDF**. The LibreOffice engine initializes (a progress indicator shows loading status), then each file is converted.
+4. A single file downloads directly as a PDF. Multiple files are packaged into `odt-converted.zip`.
+
+## Options
+
+This tool has no additional configuration. The conversion preserves the original document's formatting as closely as possible.
+
+## Output
+
+| Input Count | Output                                                        |
+| :---------- | :------------------------------------------------------------ |
+| 1 file      | Single PDF download (e.g., `document.pdf`)                    |
+| 2+ files    | ZIP archive (`odt-converted.zip`) containing one PDF per file |
+
+## Use Cases
+
+- Converting LibreOffice Writer documents to PDF for sharing with Microsoft Office users
+- Producing print-ready PDFs from academic papers written in OpenDocument format
+- Batch converting a folder of ODT templates into PDFs for distribution
+- Generating PDFs from ODT files created by automated document generation systems
+
+## Tips
+
+- The LibreOffice engine loads on first use and is cached for subsequent conversions. The initial load takes a few seconds; after that, conversions are fast.
+- Complex documents with embedded OLE objects or unusual fonts may render slightly differently than desktop LibreOffice. Test with a sample before batch converting.
+- For Word documents (`.doc`, `.docx`), use the [Word to PDF](./word-to-pdf) tool instead, which also uses the LibreOffice engine but accepts Microsoft formats directly.
+
+## Related Tools
+
+- [Word to PDF](./word-to-pdf)
+- [RTF to PDF](./rtf-to-pdf)
+- [Text to PDF](./txt-to-pdf)