Add process.info MCP tool for PEB/TEB enumeration

Expose PEB address via provider interface and query it in the
ProcessMemory plugin using NtQueryInformationProcess. The new
process.info MCP tool returns the PEB VA and enumerates TEBs by
querying thread information via NtQuerySystemInformation and
NtQueryInformationThread for each thread in the target process.

src/providers/provider.h

@@ -73,6 +73,13 @@ public:
     // Default: returns empty (scan engine falls back to [0, size())).
     virtual QVector<MemoryRegion> enumerateRegions() const { return {}; }
 
+    // Process Environment Block address (x64 PEB VA in target process).
+    // Only meaningful for live process providers. Returns 0 if unavailable.
+    virtual uint64_t peb() const { return 0; }
+
+    struct ThreadInfo { uint64_t tebAddress; uint32_t threadId; };
+    virtual QVector<ThreadInfo> tebs() const { return {}; }
+
     // --- Derived convenience (non-virtual, never override) ---
 
     bool isValid() const { return size() > 0; }