fix(runtime): Random.* in any program; value_* called directly brings the value tree

The seeded random numbers lived in the ECS runtime, so a tool or a
program of test blocks got "unknown function rng_range". They are
runtime/native/rng.ludic now, spliced on Random.* or a bare rng_*/seed
call nobody defines, and imported by core.ludic for a game. A bare
value_*/json_* call nothing in the program defines splices the value
tree the way Value.* does. Reseed.

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

examples/library/testing_random.ludic

@@ -0,0 +1,12 @@
+# testing_random.ludic — a program made only of test blocks has the runtime's namespaces too:
+# Random.range through a helper. Its runner prints:
+#   == 1 passed, 0 failed ==
+program TestingRandom {
+  function roll() -> int {
+    return Random.range(1, 6)
+  }
+  test "a roll is a die's" {
+    let r = roll()
+    expect(r >= 1 and r <= 6)
+  }
+}