Remove the experimental Windows 7 build

Drop the unsupported Windows 7 x64 portable build and everything that existed only for it:
the windows7 workflow, packaging script and docs/windows7.md; the windows7 feature and the
win7-target cfgs (plain cfg(windows) now); the Windows 7 print transport
(printing/windows7.rs); the glow renderer path; and vendor/windows-link, the patched crate
only that build used. NOTICE, README and the living docs no longer describe it; dated
change-history rows are left as they were.

apps/vectorcraft-cli/src/main.rs

@@ -46,7 +46,7 @@ mod perf;
 #[path = "../../vectorcraft/src/prefs_dir.rs"]
 mod prefs_dir;
 /// The desktop app's DirectWrite font lister, shared: exports and MCP find the same fonts.
-#[cfg(all(windows, not(target_vendor = "win7")))]
+#[cfg(windows)]
 #[path = "../../vectorcraft/src/system_fonts.rs"]
 mod system_fonts;
 
@@ -162,7 +162,7 @@ fn help() -> Result<(), String> {
 
 fn main() -> ExitCode {
     // Before any font lookup: the fonts font services load (#579).
-    #[cfg(all(windows, not(target_vendor = "win7")))]
+    #[cfg(windows)]
     system_fonts::install();
     #[cfg(target_os = "macos")]
     mac_fonts::install();