Fix 13 logic bugs and UI issues across editor, controller, and core

Round 1: Fix updateCommandRow offset, structTypeName undo, changeNodeKind
macro, shift-click kCommandRowId leak, type filter byte-vs-column bug.
Round 2: Move kFooterIdBit to core.h, add RcxEditor destructor for cursor
cleanup, defer refresh during batch ops, use newline separator in type
picker, narrow selection on double-click edit, clear hover on keyboard
scroll, guard 0x prefix from deletion, cap array count at 100k.

src/providers/provider.h

@@ -42,7 +42,7 @@ public:
 
     bool isValid() const { return size() > 0; }
 
-    bool isReadable(uint64_t addr, int len) const {
+    virtual bool isReadable(uint64_t addr, int len) const {
         if (len <= 0) return (len == 0);
         uint64_t ulen = (uint64_t)len;
         return addr <= (uint64_t)size() && ulen <= (uint64_t)size() - addr;