Bump workspace to edition 2024

- edition = "2024" in the workspace manifest and rsdosedit
- extern blocks must be unsafe: interrupts.rs ISR stubs -> unsafe extern "C"
- #[no_mangle] -> #[unsafe(no_mangle)] (efi_main, isr_dispatch)
- One missed static-mut read in free_list_insert wrapped in an explicit
  unsafe block (edition 2024 removed the implicit unsafe context inside
  unsafe fns)
- rustfmt reflows for 2024: nested if-lets become let-chains, imports
  re-sorted, rsdosedit help-screen box rows wrapped

No codegen-affecting changes. Validated: cargo check/clippy/fmt clean
(host + uefi target), make test-disk PASS, editor round-trip PASS.

1 files changed, 2 insertions, 2 deletions

diff --git a/rsnix/src/interrupts.rs b/rsnix/src/interrupts.rs
index cbd234e..2b82a3d 100644
--- a/rsnix/src/interrupts.rs
+++ b/rsnix/src/interrupts.rs
@@ -256,7 +256,7 @@ struct IntFrame {
 }
 
 /// Called from the asm common handler — dispatches to the right Rust handler.
-#[no_mangle]
+#[unsafe(no_mangle)]
 unsafe extern "C" fn isr_dispatch(frame: &IntFrame) {
     unsafe {
         match frame.vector {
@@ -344,7 +344,7 @@ pub fn init() {
 // ---------------------------------------------------------------------------
 // Extern symbols from global_asm!
 // ---------------------------------------------------------------------------
-extern "C" {
+unsafe extern "C" {
     fn isr_stub_32();
     fn isr_stub_33();
     fn isr_stub_spurious();