Ψ-W1-T1 second-round remediation: ±1-frame bounds tolerance, self-cleanup a refused render, hedge two unverified render-source inferences

Loosens the exact-bounds gate against REAPER's edge rounding; deletes the bytes a BoundsMismatch refusal writes, per prune_fs's self-cleanup carve-out.

src/shell/capture/capture_orchestrator.cpp

@@ -192,9 +192,9 @@ CaptureResult renderOffline(CaptureScope scope,
         refused.status  = CaptureStatus::MultiTrackRange;
         refused.message =
             "This range is narrower than the selected items, so it renders through "
-            "their tracks -- and those items span more than one track, which renders "
-            "one file per track. Capture one track's items at a time, or make the "
-            "range match the items' extent.";
+            "their tracks -- and those items span more than one track, which this "
+            "shape cannot land as a single file. Capture one track's items at a "
+            "time, or make the range match the items' extent.";
         return refused;
     }