feat: disasm popup, symbol separation, context menu improvements, RVA fixes

- Add Fadec x86 disassembler with hover popup for FuncPtr/void Pointer nodes
- Separate pointer symbol from address: // prefix, green comment coloring,
  independent hover/click zones (address triggers popup, symbol is passive)
- Fix RVA margin and inline local offset for pointer-expanded vtable children
  using ptrBase field threaded through composition
- Expand multi-select context menu with quick-convert, duplicate, copy address
- Remove Edit Value from hex node context menu
- Fix heatmap flickering on hex nodes (remove per-byte alternation)
- Fix popup repositioning when moving mouse between lines
- Truncate disasm popup to 6 lines with ... indicator
- Add BUILD_UI_TESTS option to skip widget tests on headless CI
- Add test_disasm with 35 test cases for disassembly and hex dump
- Add KUSER_SHARED_DATA example .rcx file

src/disasm.h

@@ -0,0 +1,15 @@
+#pragma once
+#include <QString>
+#include <QByteArray>
+#include <cstdint>
+
+namespace rcx {
+
+// Disassemble up to maxBytes of x86 code, returning formatted asm lines.
+// bitness: 32 or 64. Returns one line per instruction, prefixed with offset.
+QString disassemble(const QByteArray& bytes, uint64_t baseAddr, int bitness, int maxBytes = 128);
+
+// Format bytes as hex dump lines (16 bytes per line with ASCII sidebar).
+QString hexDump(const QByteArray& bytes, uint64_t baseAddr, int maxBytes = 128);
+
+} // namespace rcx