lib/ww + wcc + w6c + wwdump: strip *arena cascade (γ-6)

amalloc has 0 callers post-γ-2; the *arena threaded through
newnode/newscope/newtype/prim/typesinit/type{ptr,slice,array,chan,
named}/lexinit/parserinit/joindotted/checkinit/arenau64tos/cgeninit
and the scope.a / tctx.a / lex.a / parser.a / checker.a / cgen.a
fields are vestigial.

Drop `import mem;` from 15 files, remove six struct fields, strip
*arena from 14 signatures, update ~120 call sites across lib/ww +
wcc + w6c + wwdump. selfhost/test/sym_link.ww fixture drops the
newarena/freearena probe; still exits 42 on scopedefine/scopelookup.
Both main.combined.ww auto-regenerated.

Comments retidied: typ.ww "once per arena" → "once per program";
parse.ww drops "arena-build" qualifier on joindotted; sym.ww drops
mem-sibling-imports rationale.

Verified 132/132 incl. 994_w6c_ww + 995_self_rebuild byte-identity
(the primary symmetric-stages gate).

selfhost/cmd/wwdump/main.ww

@@ -12,7 +12,6 @@
 package main;
 
 import os;
-import mem;
 import tok;
 import lex;
 import ast;
@@ -99,7 +98,6 @@ export fn main(argc: i32, argv: **u8) i32 = {
 	};
 	};
 
-	let a: *arena = newarena();
 	let buf: []u8 = alloc([], sz: u64)!;
 	buf.len = sz: i32;
 	let rr: (i64 | os.oserror) = os.readall(fd, buf.ptr, sz: u64);
@@ -118,7 +116,7 @@ export fn main(argc: i32, argv: **u8) i32 = {
 	};
 
 	let l: lex;
-	lexinit(&l, a, argstr(path), buf.ptr, sz: u64);
+	lexinit(&l, argstr(path), buf.ptr, sz: u64);
 
 	if (mode == 116) {	// '-t'
 		for (true) {
@@ -130,17 +128,17 @@ export fn main(argc: i32, argv: **u8) i32 = {
 		};
 	} else { if (mode == 97) {	// '-a'
 		let ps: parser;
-		parserinit(&ps, a, &l);
+		parserinit(&ps, &l);
 		let f: *node = parsefile(&ps);
 		astprint(1i32, f);
 	} else { if (mode == 114) {	// '-r' — name resolve report
 		let ps: parser;
-		parserinit(&ps, a, &l);
+		parserinit(&ps, &l);
 		let f: *node = parsefile(&ps);
 		let tc: tctx;
-		typesinit(&tc, a);
+		typesinit(&tc);
 		let ck: checker;
-		checkinit(&ck, a, &tc);
+		checkinit(&ck, &tc);
 		// Quiet by default; flip to 1 when debugging missing names.
 		ck.verbose = 0;
 		checkfile(&ck, f);
@@ -158,7 +156,7 @@ export fn main(argc: i32, argv: **u8) i32 = {
 		if (ck.nunresolved > 0) { return 1; };
 	} else { if (mode == 99) {	// '-c' — codegen / emit asm
 		let ps: parser;
-		parserinit(&ps, a, &l);
+		parserinit(&ps, &l);
 		let f: *node = parsefile(&ps);
 		// #50: mirror w6c — run check before cgen so AST mutations
 		// from #42 (size/align/offset fold) and audit §1.8 (node.type_
@@ -166,13 +164,13 @@ export fn main(argc: i32, argv: **u8) i32 = {
 		// (the byte-identity probe for 994) would diverge from w6c_ww
 		// on any program that uses the size/align/offset typed builtins.
 		let tc: tctx;
-		typesinit(&tc, a);
+		typesinit(&tc);
 		let ck: checker;
-		checkinit(&ck, a, &tc);
+		checkinit(&ck, &tc);
 		checkfile(&ck, f);
 		if (ck.errs > 0) { return 1; };
 		let cg: cgen;
-		cgeninit(&cg, a);
+		cgeninit(&cg);
 		cgfile(&cg, f);
 	};};};};