fix(0114): gate alias-qualified calls to one-level carry, pin to target

The lowerCall namespace branch routed alias.fn() through the global
qualified registration (first-wins) at any import depth, and through the
global last-wins bare map for comptime/generic members. Plain-identifier
alias roots now resolve via the carry-aware namespaceAliasVerdict:

- visible alias (own edge or ONE flat hop): the member dispatches the
  TARGET module's own fn (namespaceFnMember + fd-keyed bareAuthorFuncId),
  so two modules' same-named aliases each call their own target.
- two direct flat imports carrying the alias to distinct targets:
  loud ambiguity diagnostic.
- alias only reachable beyond one hop: "namespace 'X' is not visible".
- foreign / builtin / #compiler members keep the literal-symbol path.

Regressions: examples 0832 (two-hop), 0833 (carried collision),
0834 (own-target pin / first-wins repair).

examples/expected/0832-modules-namespace-alias-two-hop-not-visible.exit

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

examples/expected/0832-modules-namespace-alias-two-hop-not-visible.stderr

@@ -0,0 +1,5 @@
+error: namespace 't' is not visible; #import the module that declares it
+  --> examples/0832-modules-namespace-alias-two-hop-not-visible.sx:14:19
+   |
+14 |     print("{}\n", t.helper());
+   |                   ^

examples/expected/0832-modules-namespace-alias-two-hop-not-visible.stdout

@@ -0,0 +1 @@
+

examples/expected/0833-modules-namespace-alias-carried-collision-ambiguous.exit

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

examples/expected/0833-modules-namespace-alias-carried-collision-ambiguous.stderr

@@ -0,0 +1,5 @@
+error: namespace 't' is ambiguous: aliases from multiple flat-imported modules point at different targets; declare the alias locally
+  --> examples/0833-modules-namespace-alias-carried-collision-ambiguous.sx:14:43
+   |
+14 |     print("{} {} {}\n", use_a(), use_b(), t.fx());
+   |                                           ^

examples/expected/0833-modules-namespace-alias-carried-collision-ambiguous.stdout

@@ -0,0 +1 @@
+

examples/expected/0834-modules-namespace-alias-own-target-pin.exit

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

examples/expected/0834-modules-namespace-alias-own-target-pin.stderr

@@ -0,0 +1 @@
+

examples/expected/0834-modules-namespace-alias-own-target-pin.stdout

@@ -0,0 +1 @@
+1 2