restructure: rsnix kernel + shell crate + rsdos entry point

Architecture:
  rs-dos/  (workspace root, was raisernics/)
  ├── rsnix/     — kernel lib crate (uefi, serial, gop, ps2, interrupts, memory)
  ├── shell/     — shell lib crate (prompt, commands, line input)
  ├── rsdos/     — binary crate (efi_main, init, panic handler)
  └── rsboot/    — future git submodule

No functional changes — boots to shell prompt identically.
Version auto-pulled from Cargo.toml via env!("CARGO_PKG_VERSION").

1 files changed, 2 insertions, 2 deletions

diff --git a/src/interrupts.rs b/rsnix/src/interrupts.rs
index 90d5bbb..8f2acd7 100644
--- a/src/interrupts.rs
+++ b/rsnix/src/interrupts.rs
@@ -174,7 +174,7 @@ impl KeyBuf {
         let h = self.head.load(Ordering::Acquire);
         let next = t.wrapping_add(1);
         // Full if the distance between head and tail == capacity (256).
-        if next.wrapping_sub(h) as u16 > 255 {
+        if next.wrapping_sub(h) > 255 {
             return; // drop — ring is full
         }
         unsafe {
@@ -362,7 +362,7 @@ pub fn init() {
 
         // Build the IDTR pseudo-descriptor.
         IDTR = [
-            (256u16 * 16 - 1) as u16,      // limit = 256*16 - 1
+            ((256u16 * 16 - 1)),      // limit = 256*16 - 1
             idt_ptr as u16,                // base lo
             (idt_ptr as u64 >> 16) as u16, // base mid
             (idt_ptr as u64 >> 32) as u16, // base hi