Make the background FX drain visible: a busy cursor over the panel and a footer readout that names its direction, driven off fxReclaimActivity

src/shell/panel/CLAUDE.md

@@ -62,6 +62,18 @@ live in `shell/bank_ops`, a sibling directory, not here.
 
 - **No external UI framework.** iPlug2 / JUCE / VSTGUI are rejected (DS-1). LICE +
   reused WDL pieces are the toolkit; reject any path that pulls in a new framework.
+- **The FX-drain indicator asks `fxReclaimActivity()` and decides nothing itself.**
+  `panel_input` polls it once per tick into `g_panel.fxDrain`; the footer readout and the
+  `WM_SETCURSOR` busy cursor both read that cached state, so paint and cursor cannot
+  disagree within a tick. The transport gate, the park debounce and the open-undo-block
+  stand-off are all already folded into that answer, against the reclaim queue's own pinned
+  project — do not re-evaluate any of them here, and never drive this off `fxReclaimPending`
+  (true throughout the debounce, when only the opposite direction is eligible).
+  The indicator reaches only our own window: over REAPER's arrange or mixer the cursor is
+  REAPER's, and the SDK exposes nothing host-wide. A global `SetSystemCursor` or a message
+  hook would reach further and is rejected — do not reintroduce either. `IDC_APPSTARTING`
+  is Windows-only (SWELL ships no equivalent), so on mac/Linux the readout is the whole
+  indicator.
 - **No hit-test geometry in untestable shell code.** Even when reusing a WDL piece
   (e.g. a `vwnd` control for a long scroll list), layout/hit-test math stays in pure
   CTest-covered modules — do not import a WDL control's retained-mode object model