docs: drop-onto-panel is bank-fill only

Correct ingest surface (3) in CLAUDE.md (only surface (1) assigns now) and
the drag-and-drop bullet in CONTEXT.md to bank-fill-only behavior.

CONTEXT.md

@@ -1600,11 +1600,14 @@ headers):**
 - **Drag-and-drop onto ReaSampler surfaces.** REAPER exposes **no** drag-drop registration
   API. Drop handling is on ReaSampler's *own* HWNDs via SWELL/Win32 (`WM_DROPFILES` /
   `IDropTarget` on the docked `bank_panel` HWND — the surface the panel already owns) → ingest
-  → assign. **Assess-and-flag (spike, not promised):** a drop *onto the VST3 editor window* —
-  whether the `IPlugView` HWND can accept an OS file drop and **relay it to the extension as
-  a bank-ingest request** (the instrument does not ingest; it forwards a request over an
-  agreed seam). This crosses the two-artifact boundary and the relay is unproven; if gnarly,
-  drop-onto-panel is the shipped path and drop-onto-editor is deferred.
+  (bank-fill only). Dropped files are imported into the active bank; no `assignment_request` is
+  written and no live instance's selection is affected. The bank-generation bump is retained so
+  open instances' browsers refresh to show newly available sounds. **Assess-and-flag (spike,
+  not promised):** a drop *onto the VST3 editor window* — whether the `IPlugView` HWND can
+  accept an OS file drop and **relay it to the extension as a bank-ingest request** (the
+  instrument does not ingest; it forwards a request over an agreed seam). This crosses the
+  two-artifact boundary and the relay is unproven; if gnarly, drop-onto-panel is the shipped
+  path and drop-onto-editor is deferred.
 
 **The assign seam.** The ingest action names the target instance (lean: the active/
 last-focused instance, discovered via the host context the bridge already resolves) and hands