amalloc has 0 callers post-γ-2; the *arena threaded through w6a's
init/dupstr/bufinit and the asm_.a / buf.a fields are vestigial.
Drop `import mem;` from opcodes/parse/obj/main, remove asm_.a and
buf.a struct fields, strip *arena from init/dupstr/bufinit
signatures, update 12 call sites. main.combined.ww auto-regenerated.
Comment at main.ww:36 retidied "argv/arena" → "argv-style" to match
post-strip reality.
Verified 132/132 incl. 991_w6a_ww + 995_self_rebuild byte-identity.
The file declares `package w6a;` (not a real `types` module), so
`import types;` was only the bundler file-key. The shadow against
lib/types/ blocked any w6a TU that wanted to pull lib/strings or
lib/bytes (both transitively reach `types.I64_MAX`); the w6a-local
shadow won the source-dir-first resolver, and `types.I64_MAX` came
back undefined → "ordered comparison on non-numeric".
Rename the file to its actual role — opcode + register enums
mirroring 6.out.h — and update the four import lines + Makefile
prereq. No symbol-call sites changed: every constant already
resolves unqualified inside the w6a package.
Unblocks #7 astrndup workaround comments in main.ww / parse.ww;
γ-2 (convert those two sites + delete astrndup export from
selfhost/cmd/wcc/mem.ww) becomes mechanical.
Verified 132/132 incl. 991_w6a_ww.
