feat: publish Gamertan Web Foundations preview source

Export the reviewed application-neutral package set through the exact public allowlist. Development history and private application evidence remain outside this canonical source root.

Developed with material AI assistance under maintainer review.

Signed-off-by: Cole Speelman <crspeelman@gmail.com>

auth/context.go

@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: MPL-2.0
+
+package auth
+
+import "context"
+
+type principalKey struct{}
+
+func WithPrincipal(ctx context.Context, principal Principal) context.Context {
+	return context.WithValue(ctx, principalKey{}, principal)
+}
+func PrincipalFromContext(ctx context.Context) (Principal, bool) {
+	principal, ok := ctx.Value(principalKey{}).(Principal)
+	return principal, ok
+}