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, 1 insertions, 1 deletions

diff --git a/rsdos/src/main.rs b/rsdos/src/main.rs
index 2ba5d32..a528810 100644
--- a/rsdos/src/main.rs
+++ b/rsdos/src/main.rs
@@ -38,7 +38,7 @@ fn panic(info: &PanicInfo) -> ! {
 /// The firmware hands us raw pointers (image handle, system table) that
 /// must remain valid for the lifetime of the call — a contract guaranteed
 /// by the UEFI loader.
-#[no_mangle]
+#[unsafe(no_mangle)]
 pub unsafe extern "efiapi" fn efi_main(image_handle: Handle, system_table: *mut SystemTable) -> ! {
     let st = unsafe { &mut *system_table };
     let bs = unsafe { &mut *st.boot_services };