R8.1: document content keeps the file's colours in a dark app

Pages, cells, slides and PDF pages paint as the file says in any
appearance; only the chrome around them follows dark mode. The
kernel keeps Ely's one light scheme, sent once a view, and MuPDF
no longer inverts. Reviews now run gpt-6.1-sol at xhigh.

Co-Authored-By: Claude <noreply@anthropic.com>

crates/ely-pdf-engine/src/bin/ely-pdf-worker/ffi.rs

@@ -31,7 +31,6 @@ unsafe extern "C" {
         scale: f32,
         rotate: c_int,
         tile: *const c_int,
-        dark: c_int,
         bgra: *mut u8,
     ) -> c_int;
     fn ely_text(
@@ -143,7 +142,6 @@ impl Mupdf {
         number: usize,
         (scale, rotate): (f32, i32),
         tile: [i32; 4],
-        dark: bool,
     ) -> io::Result<Vec<u8>> {
         let (w, h) = (usize::try_from(tile[2]), usize::try_from(tile[3]));
         let (Ok(w), Ok(h)) = (w, h) else {
@@ -158,7 +156,6 @@ impl Mupdf {
                 scale,
                 rotate,
                 tile.as_ptr(),
-                c_int::from(dark),
                 pixels.as_mut_ptr(),
             )
         };

crates/ely-pdf-engine/src/bin/ely-pdf-worker/main.rs

@@ -403,8 +403,7 @@ impl Worker {
                 for value in &mut tile {
                     *value = i32::try_from(ask.i64()?).map_err(io::Error::other)?;
                 }
-                let dark = ask.u64()? != 0;
-                self.drawn(id, page, (scale, rotate), tile, dark)
+                self.drawn(id, page, (scale, rotate), tile)
             }
             tag::TEXT => {
                 let (id, page) = (ask.u64()?, ask.u64()? as usize);

crates/ely-pdf-engine/src/bin/ely-pdf-worker/output.rs

@@ -101,9 +101,9 @@ impl crate::Worker {
     }
 
     /// A tile, and whether drawing it met damage.
-    pub(crate) fn drawn(&mut self, id: u64, page: usize, view: (f32, i32), tile: [i32; 4], dark: bool) -> io::Result<Vec<u8>> {
+    pub(crate) fn drawn(&mut self, id: u64, page: usize, view: (f32, i32), tile: [i32; 4]) -> io::Result<Vec<u8>> {
         unsafe { ely_watch_begin(self.mupdf.ctx) };
-        let pixels = self.mupdf.render(self.doc(id)?, page, view, tile, dark);
+        let pixels = self.mupdf.render(self.doc(id)?, page, view, tile);
         let warned = unsafe { ely_watch_end(self.mupdf.ctx) } != 0;
         if warned {
             self.note_damage(id)?;