Cut 7: retire a test Cut 6b made vacuous, and the invariant it claimed

Cut 3's harness reported OutOfArcConsumesNoDraw as "not yet reached" -- no
mutation could turn it red. Chasing that rather than accepting it found the
reason, and it is not a fixture defect.

The test asserted that a shot gated to zero draws nothing from ItemManager.
Random, so the shared stream advanced exactly as if the shot had never queued.
Cut 6b moved every roll onto a per-shot local generator seeded from (zone, shot
id), so Commit stopped touching that stream on EVERY path. The test then passed
for a reason unrelated to arcs -- it passed identically with the target dead
ahead -- and the rule it named stopped existing along with the stream it was
about. The short-circuit it guarded is now a cheap guard, not an invariant, and
Commit's comment was still asserting otherwise.

Rewritten as CombatNeverDrawsFromTheSharedStream, a Theory over both an
out-of-arc and an in-arc target, pinning the rule that IS live after 6b: no
combat path draws from the shared stream at all. Verified by hand -- restoring
the shared-stream read in Commit turns the in-arc case red while the out-of-arc
case stays green, which is exactly why the old test could not have caught it.

218 tests pass. All six mutation harnesses run clean with tree-clean PASS.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Assets/Scripts/ServerShared/FireControl.cs

@@ -290,9 +290,14 @@ public static class FireControl
 
     // R3/R4: the one roll. p_base was frozen at fire; the only thing measured live is how far the target has
     // actually strayed, by now, from where a straight-line projection of its fire-time velocity said it would
-    // be -- forgiven by the targeting system's Tracking, likewise frozen at fire. A shot gated to zero at fire
-    // (out of arc, out of range, unlocked, undetected) draws nothing here (short-circuit below): the RNG
-    // sequence is exactly as if the shot had never queued.
+    // be -- forgiven by the targeting system's Tracking, likewise frozen at fire.
+    //
+    // Cut 7: the short-circuit below (`p > 0f &&`) is a guard, NOT an invariant. It used to be one -- a shot
+    // gated to zero at fire had to draw nothing so the shared stream advanced exactly as if it had never
+    // queued -- but Cut 6b gave every shot its own generator, seeded from (zone, shot id) and discarded here,
+    // so whether a gated shot draws is unobservable from anywhere. The claim this comment used to make is
+    // gone with the stream it was about, and the test that asserted it became vacuous the same moment; what
+    // replaced it pins the live rule instead (combat touches no shared stream, on any path).
     private static ShotOutcome Commit(Zone zone, PendingShot shot, float now)
     {
         // Cut 6b, 6.1 (Soul finding 6): a shot's dice belong to the shot, not to whatever else happened to