feat(gasm): audit-instructions for arm64, riscv64 and loong64

Assisted-by: GLM 5.3 Flash

CHANGELOG.md

@@ -43,10 +43,12 @@ Unreleased changes on the `development` branch.
 - **`gasm verify --args`.**  Scalar arguments (`name=value`, decimal or
   `0x` hex) can now be supplied to a `--call` invocation alongside `--buf`
   buffers, closing the gap where only buffers could be supplied.
-- **`gasm audit-instructions`.**  Black-box diff of the amd64 encoder
-  against the installed `go tool asm`: superset encodings (gasm-only,
-  shippable via `gasm asm --format goobj`), known-but-unencodable names
-  (the backlog) and go-only names (feature gaps).
+- **`gasm audit-instructions`.**  Black-box diff of a gasm encoder
+  against the installed `go tool asm`, for amd64, arm64, riscv64 and
+  loong64 (`gasm audit-instructions <arch>`): superset encodings
+  (gasm-only, shippable via `gasm asm --format goobj`),
+  known-but-unencodable names (the backlog) and go-only names
+  (feature gaps).
 - **`gasm scaffold differential`.**  Prints a differential test skeleton
   for every `// func` signature in a kernel file: random seed states, the
   kernel call and a portable reference (`<name>Portable`), compared