fix(ir): reject non-type args to the 7 type-introspection builtins [F0.8]

size_of, align_of, field_count, type_name, type_eq, type_is_unsigned,
and is_flags silently reinterpreted a value argument as a type:
type_is_unsigned(6) read 6 as a TypeId index (types[6] = u8 -> true),
size_of(6)/size_of(true) sized its typeof (8), type_name(6) returned
types[6]'s name. Per Agra's ruling, all 7 now strictly require a type
(compile-time): a value argument is a compile error.

One shared guard (Lowering.reflectionTypeArgGuard, run at the top of
tryLowerReflectionCall) classifies each arg via reflectionArgIsType: a
spelled / compile-time type or generic type parameter (isStaticTypeArg),
or a runtime Type value (static type .any -- type_of(x), a []Type
element list[i], a Type-typed local/field/param) is accepted; anything
else is rejected with "<builtin> expects a type, got '<type>'". The
runtime path for type_name / type_is_unsigned is preserved (the {}
formatter calls type_is_unsigned(type_of(val)) at runtime). The 5
comptime-only builtins stay comptime-only (runtime reflection deferred).

Regression: examples/1144-diagnostics-reflection-builtin-needs-type.sx
(reject cases across all 7, exit 1). Unit test: reflectionArgIsType in
lower.test.zig. specs.md / readme.md document the strict type
requirement (and add the previously-undocumented align_of, type_eq,
type_is_unsigned). issues/0090 RESOLVED banner updated.

examples/1144-diagnostics-reflection-builtin-needs-type.sx

@@ -0,0 +1,28 @@
+// The 7 type-introspection builtins (size_of, align_of, field_count,
+// type_name, type_eq, type_is_unsigned, is_flags) take ONLY types. A
+// value argument is a compile-time error, not a silently-reinterpreted
+// TypeId index.
+//
+// Regression (issue 0090, attempt 2): each builtin used to accept a
+// non-type value and reinterpret it — `type_is_unsigned(6)` read 6 as a
+// TypeId and returned the signedness of types[6] (`u8` → true);
+// `size_of(true)` sized `typeof(true)` (8). The strict `$T: Type` guard
+// (`Lowering.reflectionTypeArgGuard`) now rejects any argument whose
+// static type is not `Type` and emits "<builtin> expects a type, got
+// '<type>'" at the offending argument, aborting (exit 1).
+//
+// Reject cases use `true`/`1.5` (whose types — bool/f64 — are stable)
+// rather than an integer literal, so the pinned diagnostics don't drift
+// when the int-literal default type changes.
+
+#import "modules/std.sx";
+
+main :: () {
+    print("{}\n", size_of(true));          // bool, not a type
+    print("{}\n", align_of(1.5));          // f64, not a type
+    print("{}\n", field_count(true));      // bool, not a type
+    print("{}\n", type_name(1.5));         // f64, not a type
+    print("{}\n", type_eq(true, false));   // both bool — both rejected
+    print("{}\n", type_is_unsigned(true)); // bool, not a type
+    print("{}\n", is_flags(1.5));          // f64, not a type
+}

examples/expected/1144-diagnostics-reflection-builtin-needs-type.exit

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

examples/expected/1144-diagnostics-reflection-builtin-needs-type.stderr

@@ -0,0 +1,47 @@
+error: size_of expects a type, got 'bool'
+  --> examples/1144-diagnostics-reflection-builtin-needs-type.sx:21:27
+   |
+21 |     print("{}\n", size_of(true));          // bool, not a type
+   |                           ^^^^
+
+error: align_of expects a type, got 'f64'
+  --> examples/1144-diagnostics-reflection-builtin-needs-type.sx:22:28
+   |
+22 |     print("{}\n", align_of(1.5));          // f64, not a type
+   |                            ^^^
+
+error: field_count expects a type, got 'bool'
+  --> examples/1144-diagnostics-reflection-builtin-needs-type.sx:23:31
+   |
+23 |     print("{}\n", field_count(true));      // bool, not a type
+   |                               ^^^^
+
+error: type_name expects a type, got 'f64'
+  --> examples/1144-diagnostics-reflection-builtin-needs-type.sx:24:29
+   |
+24 |     print("{}\n", type_name(1.5));         // f64, not a type
+   |                             ^^^
+
+error: type_eq expects a type, got 'bool'
+  --> examples/1144-diagnostics-reflection-builtin-needs-type.sx:25:27
+   |
+25 |     print("{}\n", type_eq(true, false));   // both bool — both rejected
+   |                           ^^^^
+
+error: type_eq expects a type, got 'bool'
+  --> examples/1144-diagnostics-reflection-builtin-needs-type.sx:25:33
+   |
+25 |     print("{}\n", type_eq(true, false));   // both bool — both rejected
+   |                                 ^^^^^
+
+error: type_is_unsigned expects a type, got 'bool'
+  --> examples/1144-diagnostics-reflection-builtin-needs-type.sx:26:36
+   |
+26 |     print("{}\n", type_is_unsigned(true)); // bool, not a type
+   |                                    ^^^^
+
+error: is_flags expects a type, got 'f64'
+  --> examples/1144-diagnostics-reflection-builtin-needs-type.sx:27:28
+   |
+27 |     print("{}\n", is_flags(1.5));          // f64, not a type
+   |                            ^^^

examples/expected/1144-diagnostics-reflection-builtin-needs-type.stdout

@@ -0,0 +1 @@
+