ludic.base, ludic.wildlife, ludic.npc: fact records reused, not made per fact

wl_fact made a new WildFact per fact, about one a frame, and Ludic never gives one back. ludic.base's q_unheld(q, pool, out) lists the records a queue no longer holds: neither waiting nor handed out by its last drain, which is good until the next drain. ludic.wildlife and ludic.npc now keep a pool, hand out a free record, and make a new one only when every record is held. Taking a record writes the state, so wl_fact / np_fact and the few callers holding their state read-only take it mut. Tests: q_unheld's rules (an empty drain holds on, the safe side); 3000 prints drained frame by frame use at most 4 records; 500 arrivals drained turn by turn use at most 4. base 37, wildlife 27, npc 17; all packages 420.

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

packages/ludic.wildlife/tests/crowd_test.ludic

@@ -83,4 +83,14 @@ program WildCrowdTest {
     wildlife_clear(wildlife_st)
     expect(not wildlife_listed(wildlife_st, a))
   }
+
+  test "a fact a frame, drained each frame, makes a few records and then reuses them" (wildlife_st: mut WildlifeState, wildlife_tests_fake_st: mut WildlifeTestsFakeState) {
+    let a = walker(wildlife_st, wildlife_tests_fake_st)
+    for k in 1 .. 3001 {
+      wildlife_moved(wildlife_st, a, 0.0, -3.0 * float(k), 0.0, -1.2)
+      let fs = q_drain(wildlife_facts(wildlife_st))
+      for i in 0 .. len(fs) { expect_eq(fs[i].what, WILD_PRINT) }
+    }
+    expect(wildlife_fact_records(wildlife_st) <= 4)
+  }
 }