fix(bank_panel): drive new-content baseline re-arm from persist's load signal

The detector re-armed its GuidBaseline on a pointer compare (proj != lastProject),
a weaker signal than persist's GUID-primary identity. On a load onto a recycled
ReaProject* the baseline never reset, so the just-loaded project's pre-existing
tracks diffed against the previous project and were mass-tagged into the active
mode — opening a Design-saved project mis-tagged its Arrange tracks. Re-arm now
rides persist's authoritative load signal via bankPanelNotifyProjectLoaded().

src/bank_panel.h

@@ -50,6 +50,17 @@ std::vector<std::string> bankPanelSelectedSampleIds();
 // reflected without the panel diffing the bank itself.
 void bankPanelRefresh();
 
+// Notifies the panel that persist just (re)loaded a project's view model (membership +
+// active mode). main.cpp calls this on the exact tick it drains persist's load signal
+// and reapplies the active mode. It re-arms the new-content detector so the just-loaded
+// project's PRE-EXISTING content is taken as the baseline (reported as nothing new),
+// never diffed against the previously-open project and mass-tagged into the active mode.
+// This coordinates the detector's project-identity signal with persist's authoritative
+// (GUID-primary) one — the two can no longer diverge on a recycled ReaProject* address,
+// which is what caused a project opened in Design to mis-tag its Arrange tracks. READ/
+// arm of panel state only; no project or bank mutation.
+void bankPanelNotifyProjectLoaded();
+
 // The panel's current tail-mode setting (mode + Manual length), read by the plain
 // CAPTURE_ITEM / CAPTURE_TRACK actions when building a CaptureRequest so a capture
 // applies whatever the panel toggle is set to. Default None (exact bounds) — a