parse: enforce strict-package — reject package-less files (#24a)

Flip the soft-default to a hard "missing package clause" error symmetrically in
both stages (cmd/wcc/parse.c + lib/ww/syntax/parse.ww): the first real decl of a
primary section with empty pathmod/resetmod and no seen clause is now rejected.
Closes the documented soft-default divergence (the 63-wrapper carve-out).

The gate flip can't be split from the migration it breaks, so this is one atomic
commit: ~80 test/wcc wrappers gain `package main;` via a shared wwtestpkg.h
helper, 6 data fixtures plus 17 asm-grep assertions update for the bare->main.<leaf>
root-helper mangle shift, and rt/ declares `package rt;` with @symbol pinning the
bare rt_ensure/rt_malloc linker names.

Root mangling narrows: the executable entry `main` stays bare (existing
carve-out), but root helper symbols become main.X. The #84 cluster is rewritten
to assert main.run distinct from aa.run/test.run; its cgen fix and bare machinery
are retained — still load-bearing for package-less module-reset deps. New
table-driven test 782_strict_package.c (6 rows, both stages).

Retiring //ww:module-reset is deferred to #24b: it is load-bearing (clears the
.wwi pathmod so the body's package clause asserts), not a vestige; fusing its
removal here would be a silent mismatch.

All byte-id gates green; full make test reports "all 335 tests passed".

cmd/wcc/parse.c

@@ -1407,18 +1407,16 @@ parsefile(Parser *p)
 	Pos pp = { p->l->file, 1, 1 };
 	Node *file = newnode(p->a, N_FILE, pp);
 	Node *head = NULL, *tail = NULL;
+	int sawpackage = 0;
 	while (p->cur.kind != TK_EOF) {
-		/* `package foo;` — directory-as-module declaration. Each
-		 * .ww file's section in a concatenated stream begins with
-		 * one; a single-file or fragment input may omit it (curmod
-		 * stays NULL and decls are treated as primary).
-		 *
-		 * Retained divergence from brief: the strict missing-`package`
-		 * error was softened to silent-default to keep 63 inline-source
-		 * test wrappers (200_parse, 100_lex, 300_check, ...) parsing.
-		 * See task #23 for the wrapper migration that unblocks the
-		 * strict check. Rule 7 + rule 8 documentation. */
+		/* `package foo;` — directory-as-module declaration. Every
+		 * primary section opens with one (`package main;` for an
+		 * executable); a missing clause on the first real decl is a
+		 * hard error (strict-package, #24a). Imported (pathmod) and
+		 * sep primary-reset (resetmod) regions carry identity
+		 * out-of-band and are exempt. */
 		if (p->cur.kind == TK_MODULE) {
+			sawpackage = 1;
 			advance(p);
 			const char *name = expectident(p);
 			expect(p, TK_SEMI);
@@ -1457,6 +1455,7 @@ parsefile(Parser *p)
 		 * leaf `package` clause, and are flagged imported (gates the
 		 * root-only bare-`main` rule, #32). */
 		if (p->cur.kind == TK_MODPATH) {
+			sawpackage = 0;
 			p->pathmod = p->cur.text;
 			p->curmod = p->cur.text;
 			p->resetmod = NULL;
@@ -1472,6 +1471,7 @@ parsefile(Parser *p)
 		 * directive after a mid-file `package` would strip subsequent
 		 * decls to bare — that usage is deliberate-only. */
 		if (p->cur.kind == TK_MODRESET) {
+			sawpackage = 0;
 			/* #57: a path-carrying reset (sep primary body) mangles
 			 * decls on the dotted path so definer == importer, but
 			 * leaves imported==0 (curmod set, pathmod NULL) so -c
@@ -1498,6 +1498,16 @@ parsefile(Parser *p)
 			}
 			continue;
 		}
+		/* strict-package: a primary section's first real decl must be
+		 * preceded by a `package` clause. Imported (pathmod) and sep
+		 * primary-reset (resetmod) regions carry identity out-of-band,
+		 * so they are exempt. Wording mirrors Go's missing-`package`
+		 * diagnostic (rule 5; Hare has no clause to port). */
+		if (p->pathmod == NULL && p->resetmod == NULL && !sawpackage) {
+			errorf(p->cur.pos, "missing package clause");
+			p->errs++;
+			sawpackage = 1;
+		}
 		Node *attrs = parseattrs(p);
 		int exp = accept(p, TK_EXPORT);
 		Node *d = NULL;