fix: capacities single-sourced in types (display MAX_WINDOWS/BUFFER_PAGES, storage MAX_CLIENTS), display + storage budgets derived from them, const asserts on VA layouts; kernel regions 64 -> 256

crates/servers/display-server/src/host.rs

@@ -16,8 +16,11 @@ use crate::windows::MAX_WINDOWS;
 /// a 1280x800 window; high, clear of the GPU's mappings and of the heap,
 /// which grows from the bottom.
 const BUFFERS_VA: usize = 0x1000_0000;
-const BUFFER_SPAN: usize = 0x0040_0000;
 const PAGE: usize = 4096;
+const BUFFER_SPAN: usize = types::display::window::BUFFER_PAGES * PAGE;
+// Every window's buffer fits between here and the themes' reading buffer
+// (0x1800_0000), below the heap's end.
+const _: () = assert!(BUFFERS_VA + MAX_WINDOWS * BUFFER_SPAN <= 0x1800_0000 && 0x1800_0000 < types::layout::HEAP_END);
 
 pub struct KernelHost {
     /// The display's own endpoint, which window capabilities are minted

crates/servers/display-server/src/windows.rs

@@ -7,7 +7,7 @@
 
 use types::display::window::{BADGE, NAME_BYTES};
 
-pub const MAX_WINDOWS: usize = 8;
+pub use types::display::window::MAX_WINDOWS;
 /// Events received and not yet polled by the window in front.
 const QUEUED: usize = 32;