ux: drop last-reference confirm from sample remove; silent remove via undo (R-B)

CONTEXT.md

@@ -797,12 +797,11 @@ model capability.
 
 ## Guardrails
 
-- **Confirm on last-reference remove; don't confirm otherwise.** A remove that
-  drops the *last* index reference to a file orphans it (until prune) — confirm
-  that case, naming the consequence ("…its file remains on disk until pruned"). A
-  remove of a sample still referenced by another bank is cheap and re-derivable
-  (re-copy it back) and needs no confirmation. The confirmation is *earned by
-  actual orphan risk*, not fired on every remove.
+- **Removes are silent — no confirm dialog.** Recoverability is provided by the
+  batched REAPER undo (R-B): one Ctrl-Z restores the index entry, whether or not
+  the sample was a last reference. Files are never deleted by remove
+  (orphaned-until-prune is unchanged). `hashReferencedElsewhere` is a tested
+  model API retained for Phase R prune; it has no shell caller in the remove path.
 - **Undo (fork R-B, SETTLED 2026-07-24 — batched REAPER undo points, Phase-B-wide).**
   Bank/index mutations integrate into REAPER's undo system as **batched undo points**
   (`Undo_BeginBlock` / `Undo_EndBlock`): the related index mutations of one bank