Rewrite README around download, install steps, and FAQ

[phalladar]

Summary

Rewrites the README so a regular Mac user can download and install MacDirStat in a few seconds, and so search engines and AI assistants can find and quote it accurately.

• Top of the page: a keyword-focused title, a one-sentence definition, a Download button pointing at releases/latest/download/MacDirStat.zip, real badges (latest release, macOS 15+, MIT), and the screenshot with descriptive alt text.
• Install, update, uninstall: four install steps, Full Disk Access using the banner from feat: prompt for Full Disk Access on the welcome screen #5 (the permission carries over to updates for the signed download), plus updating and uninstalling.
• "How to see what's taking up space on your Mac": a step-by-step guide.
• FAQ with question headings, each answered in its first sentence: WinDirStat/WizTree/DaisyDisk alternatives, safety and privacy, Intel support, Full Disk Access, why totals differ from macOS Storage, File Size vs Allocated Size, what the colors mean, external drives.
• Lower down: neutral alternatives, build from source, architecture, contributing, license.

Corrected claims

• The scanner uses opendir/readdir/fstatat with parallel task groups, not BSD fts.
• Removed "speed that beats FileManager-based tools", since there's no benchmark behind it.
• "200+ extension mappings" is now "~190" (there are 188 unique ones).
• GrandPerspective and OmniDiskSweeper are free, so the README no longer calls MacDirStat a "free alternative" to them.
• WizTree now has a macOS version (WizTreeMac), per its site.
• Double-click drill-down is no longer advertised. Most of the treemap is files, so it rarely triggers.

Feature claims, UI labels and the color table were checked against the source.

Merge order

Merge this after v0.1.0 is published. Until then, the download button and the release badge point at a release that doesn't exist yet.

🤖 Generated with Claude Code