Ship the GPL text, and show it in the installer

The repository declared GPL-3.0-or-later and carried no copy of it;
the Arch package pointed at the system's shared text and nothing else
needed one. The installer does: a licence page needs a file to show,
and the moment before installation is where the terms can still change
a decision. The standard text, at the root where every convention
looks for it, converted to CRLF at packaging time because a Windows
edit control draws a bare LF as nothing.

packaging/windows/darkroom.nsi

@@ -6,13 +6,8 @@
 ;
 ;   makensis -DVERSION=0.12.0 -DSTAGE=/path/to/staging -DOUT=/path/to/setup.exe darkroom.nsi
 ;
-; STAGE holds exactly what §5.2 installs: darkroom.exe and models\.
+; STAGE holds exactly what §5.2 installs: darkroom.exe, models\ and LICENSE.
 ; package.sh assembles it and applies the LFS-pointer guard before this runs.
-;
-; No licence page yet: the repository carries no LICENSE file (the Arch package
-; points at the system's shared GPL text), and a page needs a file to show.
-; Adding one at the root is the whole change; `!insertmacro MUI_PAGE_LICENSE`
-; then goes before the directory page.
 
 ; A 64-bit installer, not NSIS's default 32-bit stub. The application is
 ; x86_64 only, so nothing is lost; and it means the smoke test runs under a
@@ -60,6 +55,9 @@ VIAddVersionKey "FileDescription" "${NAME} installer"
 
 !include "MUI2.nsh"
 !define MUI_ABORTWARNING
+; The GPL, shown rather than linked, for the same reason faces.md §2.2 gives
+; for the model grant: the moment it can still change a decision.
+!insertmacro MUI_PAGE_LICENSE "${STAGE}\LICENSE"
 !insertmacro MUI_PAGE_DIRECTORY
 !insertmacro MUI_PAGE_INSTFILES
 !insertmacro MUI_UNPAGE_CONFIRM
@@ -70,6 +68,7 @@ Section "DarkRoom" SecMain
   SectionIn RO
   SetOutPath "$INSTDIR"
   File "${STAGE}\darkroom.exe"
+  File "${STAGE}\LICENSE"
 
   ; The seven model files (four face, three scene), beside the executable,
   ; which is where `library::system_face_models_dirs` looks on Windows —
@@ -112,6 +111,7 @@ Section "Uninstall"
   ; building is the destructive default this project argues against
   ; everywhere else, so the confirm page says where those directories are.
   Delete "$INSTDIR\darkroom.exe"
+  Delete "$INSTDIR\LICENSE"
   Delete "$INSTDIR\uninstall.exe"
   RMDir /r "$INSTDIR\models"
   RMDir "$INSTDIR"