Add documentation for all PDF tools

docs/tools/tiff-to-pdf.md

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+---
+title: TIFF to PDF
+description: Convert single and multi-page TIFF images to PDF format in your browser with full page support.
+---
+
+# TIFF to PDF
+
+Convert TIFF files to PDF, including multi-page TIFFs. Each page (or "IFD") in a TIFF file becomes a separate page in the output PDF. This is especially useful for scanned documents, faxes, and medical images that are commonly stored as multi-page TIFFs.
+
+## Supported Formats
+
+| Format | Extensions      |
+| :----- | :-------------- |
+| TIFF   | `.tiff`, `.tif` |
+
+## How It Works
+
+1. Click the upload area or drag and drop your TIFF files.
+2. Review the file list and manage it as needed.
+3. Click **Convert to PDF**. The result downloads as `from_tiff.pdf`.
+
+The tool decodes each TIFF file using a JavaScript TIFF decoder, extracting every page's raw RGBA pixel data. Each page is rendered onto a canvas, exported as PNG, and embedded in the PDF. Page dimensions match the original TIFF pages.
+
+## Options
+
+This tool does not expose additional quality settings. Images are embedded at their native resolution.
+
+## Use Cases
+
+- Converting multi-page fax documents (TIFF-F) to a more portable PDF format
+- Turning scanned document archives stored as TIFF into searchable PDFs (combine with the OCR tool afterward)
+- Processing medical imaging files (pathology slides, radiology exports) that use TIFF
+- Converting GIS or satellite imagery TIFF files into shareable documents
+
+## Tips
+
+- Multi-page TIFFs are fully supported. A 10-page TIFF will produce a 10-page PDF. You do not need to split the TIFF first.
+- Very large TIFF files (hundreds of megabytes) may take longer to process since the entire file must be decoded in browser memory.
+- If you need OCR on the resulting PDF, run it through the [OCR PDF](./ocr-pdf) tool after conversion.
+
+## Related Tools
+
+- [Images to PDF](./image-to-pdf)
+- [BMP to PDF](./bmp-to-pdf)
+- [JPG to PDF](./jpg-to-pdf)