fix(lower): free-fn UFCS auto-address-of + lazy lowering (issue 0063)

A free function called via UFCS (recv.fn(args)) whose first param is *T
was passed the receiver by value (LLVM "Call parameter type does not
match function signature"), and a function reached only via UFCS was
declared but never emitted (undefined symbol at link).

The bare-name UFCS fallback now mirrors the qualified-method path: it
lazily lowers the target body and calls fixupMethodReceiver +
coerceCallArgs, so the value receiver gets the same implicit address-of
as a struct-defined method and mutations through *T are visible.

Regression: 0039-basic-free-fn-ufcs-pointer-receiver.sx.

examples/expected/0039-basic-free-fn-ufcs-pointer-receiver.exit

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

examples/expected/0039-basic-free-fn-ufcs-pointer-receiver.stderr

@@ -0,0 +1 @@
+

examples/expected/0039-basic-free-fn-ufcs-pointer-receiver.stdout

@@ -0,0 +1,2 @@
+a=11 b=12 n=12
+after reset n=0