feat(debug): port the debugger to FreeBSD

Assisted-by: GLM 5.3 Flash

CHANGELOG.md

@@ -9,6 +9,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- **The FreeBSD port of the debugger.**  `gasm debug` runs on FreeBSD on
+  amd64, arm64 and riscv64: the same interactive surface as on Linux —
+  breakpoints, hardware watchpoints (x86 debug registers, the arm64 debug
+  register file), single-stepping, register and memory access — behind the
+  kernel's own ptrace requests, with tracee memory through `PT_IO` and
+  stop reports through `PT_LWPINFO`.  The JIT substrate maps executable
+  memory through `golang.org/x/sys/unix`, so `verify` builds on FreeBSD
+  too.  The pipeline compile-gates all three architectures; live
+  validation awaits a FreeBSD machine.
 - **Workspace-wide navigation in the language server.**  `gasm lsp` indexes
   the `.s` files under the workspace root beyond the documents the editor
   has open, so go-to-definition, find references and workspace symbol search