Add the FX reclaimer: a debounced, time-boxed convergence loop that offlines parked chains and restores returning ones off the switch path

src/shell/view/view.cpp

@@ -13,6 +13,7 @@
 
 #include "core/view/solo_cache.h"
 #include "core/view/view_tree.h"
+#include "shell/view/fx_reclaim.h"
 #include "shell/view/view_lanes.h"
 #include "shell/view/view_park.h"
 #include "shell/view/view_reconcile.h"
@@ -201,6 +202,12 @@ bool applyMode(ViewModeModel& model, const std::string& targetModeId, ReaProject
     // The tool's own account of what it just left driven — the only one that survives
     // an undo rolling the model back underneath it.
     noteAppliedState(project, model);
+
+    // Every membership, snapshot and active-mode mutation in the system reaches the
+    // project through this call, so this is the whole invalidation surface: what the FX
+    // chains SHOULD be has just changed, and the reclaimer's queue is a cache of that
+    // intent, never state.
+    invalidateFxReclaim();
     return true;
 }