v0.5.7: allocator corruption guard + full register dump for real-hardware repro

The OptiPlex #GP (vec=13 in __rust_dealloc) frees a garbage pointer: the
back-pointer at [ptr-8] is clobbered by the time the shell drops its
Parsed struct.  A blind store to the bogus block header was an opaque
#GP — now it is a readable report:

- dealloc validates the back-pointer (in-heap block, sane size, in-use)
  before trusting it; on failure it prints ptr/block/heap range, the
  memory around the block header, and the live stack chain, writes the
  crash band + crash.log, and halts (memory.rs: heap_guard_report).
- fault dumps now carry the full register set (rax..rdi, rbx, r8..r15)
  so the next repro shows the exact freed ptr and clobbered value.
- new 'corrupt' shell hook deliberately clobbers a live block's
  back-pointer to prove the guard fires (test-fault-style halt).

Verified: test-msg/test-disk/test-fault pass; corrupt hook reports
ptr=.. block=0xdeedbeef... with mem dump instead of #GP. rs-dos.img
rebuilt with the release kernel.

1 files changed, 1 insertions, 1 deletions

diff --git a/Cargo.toml b/Cargo.toml
index 76139bb..b55a0aa 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,7 +3,7 @@ resolver = "2"
 members = ["rsnix", "shell", "rsdos", "rsdosedit"]
 
 [workspace.package]
-version = "0.5.5"
+version = "0.5.7"
 edition = "2024"
 
 # no_std UEFI kernel: no unwinder available, so panic must abort.