fix(stdlib/E4): route reflection/literal/value/match bare-type sites through the non-transitive gate

attempt-3 closed the leaf + parameterized-head leaks but several more
sites still resolved an UNQUALIFIED type name via the global
type_alias_map / findByName / type_bridge.resolveAstType without the
single-hop visibility gate, so a 2-flat-hop bare type leaked through:

  - resolveTypeArg (reflection / size_of / align_of / type_name / type_eq):
    identifier + type_expr leaves now gate via headTypeLeak; the wrapped /
    structural forms (*T, [N]T, []T, ?T, fn-ptr, tuple) route through the
    already-gated resolveTypeWithBindings so each inner leaf recurses the
    source-aware resolveNominalLeaf.
  - resolveTupleLiteralTypeArg: each element leaf is resolved through the
    source-aware resolver before the delegated build, so (COnly, s64) is
    gated.
  - resolveArrayLiteralType (T.[...] typed array/vector-literal head):
    identifier + type_expr leaves gate via headTypeLeak.
  - type-as-value lowerExpr identifier (x: Type = COnly, x == COnly).
  - type-category match arm (case COnly:).

Qualified ns.X / 1-hop / source-pinned library-internal references stay
exempt (the gate falls through for reachable / unauthored names, and
returns the existing "unresolved type" diagnostic for genuinely-undeclared
names). README notes the type gate holds wherever a bare type name is
named. New regressions 0765 (2-hop reject) / 0766 (1-hop pass).

examples/expected/0765-modules-import-reflection-type-non-transitive.exit

@@ -0,0 +1 @@
+1

examples/expected/0765-modules-import-reflection-type-non-transitive.stderr

@@ -0,0 +1,17 @@
+error: type 'Nums' is not visible; #import the module that declares it
+  --> /Users/agra/projects/sx/examples/0765-modules-import-reflection-type-non-transitive.sx:22:27
+   |
+22 |     print("{}\n", size_of(Nums));
+   |                           ^^^^
+
+error: type 'COnly' is not visible; #import the module that declares it
+  --> /Users/agra/projects/sx/examples/0765-modules-import-reflection-type-non-transitive.sx:23:28
+   |
+23 |     print("{}\n", size_of(*COnly));
+   |                            ^^^^^
+
+error: type 'Nums' is not visible; #import the module that declares it
+  --> /Users/agra/projects/sx/examples/0765-modules-import-reflection-type-non-transitive.sx:24:11
+   |
+24 |     xs := Nums.[1, 2];
+   |           ^^^^

examples/expected/0765-modules-import-reflection-type-non-transitive.stdout

@@ -0,0 +1 @@
+

examples/expected/0766-modules-reflection-type-direct-ok.exit

@@ -0,0 +1 @@
+0

examples/expected/0766-modules-reflection-type-direct-ok.stdout

@@ -0,0 +1,3 @@
+16
+8
+1 2