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.cpp

@@ -0,0 +1,76 @@
+#include "disasm.h"
+
+extern "C" {
+#include <fadec.h>
+}
+
+namespace rcx {
+
+QString disassemble(const QByteArray& bytes, uint64_t baseAddr, int bitness, int maxBytes) {
+    if (bytes.isEmpty() || (bitness != 32 && bitness != 64))
+        return {};
+
+    int len = qMin((int)bytes.size(), maxBytes);
+    const auto* buf = reinterpret_cast<const uint8_t*>(bytes.constData());
+
+    QString result;
+    int off = 0;
+    while (off < len) {
+        FdInstr instr;
+        int ret = fd_decode(buf + off, len - off, bitness, baseAddr + off, &instr);
+        if (ret < 0)
+            break;
+
+        char fmtBuf[128];
+        fd_format(&instr, fmtBuf, sizeof(fmtBuf));
+
+        if (!result.isEmpty())
+            result += QLatin1Char('\n');
+        result += QStringLiteral("%1  %2")
+            .arg(baseAddr + off, bitness == 64 ? 16 : 8, 16, QLatin1Char('0'))
+            .arg(QString::fromLatin1(fmtBuf));
+
+        off += ret;
+    }
+    return result;
+}
+
+QString hexDump(const QByteArray& bytes, uint64_t baseAddr, int maxBytes) {
+    if (bytes.isEmpty())
+        return {};
+
+    int len = qMin((int)bytes.size(), maxBytes);
+    QString result;
+
+    for (int off = 0; off < len; off += 16) {
+        int lineLen = qMin(16, len - off);
+
+        if (!result.isEmpty())
+            result += QLatin1Char('\n');
+
+        // Address
+        bool wide = (baseAddr + len > 0xFFFFFFFFULL);
+        result += QStringLiteral("%1  ").arg(baseAddr + off, wide ? 16 : 8, 16, QLatin1Char('0'));
+
+        // Hex bytes
+        for (int i = 0; i < 16; i++) {
+            if (i < lineLen) {
+                uint8_t b = static_cast<uint8_t>(bytes[off + i]);
+                result += QStringLiteral("%1 ").arg(b, 2, 16, QLatin1Char('0'));
+            } else {
+                result += QStringLiteral("   ");
+            }
+            if (i == 7) result += QLatin1Char(' ');
+        }
+
+        // ASCII
+        result += QLatin1Char(' ');
+        for (int i = 0; i < lineLen; i++) {
+            char c = bytes[off + i];
+            result += (c >= 0x20 && c < 0x7f) ? QLatin1Char(c) : QLatin1Char('.');
+        }
+    }
+    return result;
+}
+
+} // namespace rcx