feat(lang): module NAME uses A, B - a module reaches only the modules it names

A reference from a module that declares uses into a module it does not
name is refused, exported or not, naming the use and the fix. A module
with no uses clause keeps the old rule; a package's module is always
usable; a friend is not held to it; a cycle in the declared graph is
refused; LUDIC_VIS_REPORT=1 lists the violations as uses: lines. Reseed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

examples/modules/uses.ludic

@@ -0,0 +1,12 @@
+# uses.ludic — L3: `module fishing uses base` names the only modules fishing may reach; the program
+# itself is in no module, so it may call anything exported. A module with no `uses` line keeps the
+# old rule, which is how the rule comes into a codebase one module at a time.
+#
+# Running it prints:  8 3
+import "valley/base"
+import "valley/fishing"
+program Uses {
+  entry {
+    print(`{cast(3)} {bait()}`)
+  }
+}

examples/modules/valley/base/index.ludic

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+# base/index.ludic - a module with no uses line keeps the old rule: its exports are anyone's
+module base
+export function bait() -> int {
+  return 3
+}

examples/modules/valley/fishing/catch.ludic

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+# fishing/catch.ludic - inherits `module fishing uses base` from its barrel
+export function cast(times: int) -> int {
+  return times * bait() - 1
+}

examples/modules/valley/fishing/index.ludic

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+# fishing/index.ludic - fishing names the one module it may reach
+module fishing uses base
+import "catch.ludic"