Add documentation for all PDF tools

docs/tools/linearize-pdf.md

@@ -0,0 +1,49 @@
+---
+title: Linearize PDF
+description: Optimize PDF files for fast web viewing with progressive loading. Also known as "Fast Web View" optimization.
+---
+
+# Linearize PDF
+
+Linearization restructures a PDF so the first page can be displayed before the entire file has downloaded. Adobe calls this "Fast Web View." If you host PDFs on a website or serve them through a document portal, linearization makes them feel significantly faster to open.
+
+## How It Works
+
+1. Upload one or more PDF files.
+2. Click **Linearize PDF(s)**.
+3. Download the results as a ZIP archive containing all linearized files.
+
+There are no settings to configure. The tool uses QPDF's `--linearize` flag, which rearranges the internal structure of the PDF without altering its visual content.
+
+## What Linearization Does
+
+- Reorders PDF objects so the first page's data appears at the beginning of the file
+- Adds a linearization dictionary and hint tables so viewers know where to find each page
+- Enables byte-range requests -- a browser can fetch just the first page without downloading the whole file
+- Cleans up the cross-reference table for efficient random access
+
+## Features
+
+- Batch processing of multiple PDFs in a single operation
+- Output preserves all content, fonts, images, and interactive elements
+- Uses QPDF (WebAssembly) for reliable, standards-compliant linearization
+- Results are packaged into a ZIP for easy download
+
+## Use Cases
+
+- Hosting PDF reports on a website where users expect instant page display
+- Embedding PDFs in web applications with in-browser viewers
+- Publishing PDF catalogs or manuals accessed over slow mobile connections
+- Preparing documents for content delivery networks (CDNs) that support byte-range serving
+
+## Tips
+
+- Linearize after all other edits are done. Any subsequent modification (merging, adding pages) will break the linearization.
+- Combine with Compress PDF for the smallest, fastest-loading PDFs possible.
+- Linearization adds a small amount of overhead to file size (typically under 1%).
+
+## Related Tools
+
+- [Compress PDF](./compress-pdf) -- reduce file size before linearizing
+- [Repair PDF](./repair-pdf) -- fix structural issues that prevent linearization
+- [Remove Metadata](./remove-metadata) -- strip metadata before publishing online