feat: extract typeIndex from PDB symbols and add symbols.importType MCP tool

extractPdbSymbols() was reading S_GDATA32/S_GTHREAD32 records which
contain a typeIndex field linking the symbol to its type definition in
the TPI stream, but this field was discarded — only name + RVA were
kept. This meant loading symbols gave you address resolution but no
way to automatically import the type associated with a global variable.

Changes:
- PdbSymbol now carries typeIndex (0 = no type info / public symbol)
- extractPdbSymbols() captures typeIndex from all global data symbols
- PdbSymbolSet stores nameToTypeIndex mapping alongside nameToRva
- New importTypeForSymbol() follows LF_POINTER/LF_MODIFIER chains to
  find the underlying UDT/enum and imports it with full recursive children
- New symbols.importType MCP tool: given "ntdll!g_pShimEngineModule",
  resolves its typeIndex, imports the type definition from the PDB, and
  merges it into the active project
- loadPdbIntoStore() helper consolidates the extract+store pattern with
  type index support

src/symbolstore.cpp

@@ -52,6 +52,26 @@ int SymbolStore::addModule(const QString& moduleName, const QString& pdbPath,
     return count;
 }
 
+void SymbolStore::addModuleTypeIndices(const QString& moduleName,
+                                       const QHash<QString, uint32_t>& nameToTypeIndex) {
+    QString canonical = resolveAlias(moduleName);
+    auto it = m_modules.find(canonical);
+    if (it == m_modules.end()) return;
+    it->nameToTypeIndex = nameToTypeIndex;
+}
+
+uint32_t SymbolStore::typeIndexForSymbol(const QString& qualifiedSymbol) const {
+    int bangIdx = qualifiedSymbol.indexOf('!');
+    if (bangIdx <= 0 || bangIdx >= qualifiedSymbol.size() - 1)
+        return 0;
+    QString modPart = qualifiedSymbol.left(bangIdx);
+    QString symPart = qualifiedSymbol.mid(bangIdx + 1);
+    QString canonical = resolveAlias(modPart);
+    auto modIt = m_modules.find(canonical);
+    if (modIt == m_modules.end()) return 0;
+    return modIt->nameToTypeIndex.value(symPart, 0);
+}
+
 void SymbolStore::unloadModule(const QString& moduleName) {
     QString canonical = resolveAlias(moduleName);
     m_modules.remove(canonical);