The installer's file types become a Components tree, with a Shortcuts & Right-Click Menu page

[WillTDA]

The installer's two pages after "Who it's for", and the shortcuts they ask about.

• Choose File Types is MUI's Components page: a branch per file type group, expanded, with a box per extension and the Open With line above the tree. An update skips it. Its sections only hold the ticks: customInstall reads them. electron-builder's own "install" section is hidden by its index (SectionSetText in customInit), and customInstall has a compile-time !if ${INSTALL_SECTION_ID} != <n> !error, so if electron-builder ever moves that section the build fails instead of shipping a stray box.
• Shortcuts & Right-Click Menu: "Add a desktop shortcut", "Add a Start menu shortcut" and the right-click entry's box, all ticked. An app without an entry gets "Shortcuts". The choices are kept as KitDesktopShortcut and KitStartMenuShortcut, and the new silent switches are /NODESKTOPSHORTCUT (or --no-desktop-shortcut) and /NOSTARTMENUSHORTCUT.
• Each shortcut is matched to its box after electron-builder's own: an unticked one is removed, and a ticked one that's missing is made. An update never makes one, so a shortcut the person deleted stays deleted. Without a Start menu shortcut, $launchLink is the exe, so Run and --force-run still start the app.
• Tick All, Untick All and the page's column limit go; the tree scrolls. A group's name can't start with - or ! (NSIS would hide the branch or make it bold).
• The demo gains a second group, Data File (json, csv).
• scripts/capture-installer.ps1 runs the installer and uninstaller with their pages showing, clicks Next with Win32 messages and saves a PNG of each page. Windows CI runs it after check-installer.ps1 and uploads the PNGs as a 3-day artifact.
• check-installer.ps1 now also checks the shortcuts:
  • a fresh install makes both;
  • the switches remove both, and --updated keeps them gone;
  • with the kept choices removed, a reinstall makes them again;
  • --force-run without a Start menu shortcut starts the app;
  • uninstalling removes both;
  • for everyone, it checks the same in the common Desktop and Start menu.
• docs/building.md: the pages, the switches, and a note that without a Start menu shortcut Windows doesn't deliver the app's notifications (Electron still reports them as shown).

Checked locally: npm test 256/256. The demo, a 22-type shape and an entry-only shape all compile under makensis -WX, and the capture of each was looked at. check-installer.ps1 passed per user; the install for everyone runs in CI.