RDP session fixes: correct keyboard scancodes, clipboard sync, cursor shapes

Fix RDP keyboard input using FreeRDP's authoritative X11-keycode-to-scancode
table instead of ad hoc bit math, which misread punctuation keys as unrelated
letter keys (e.g. apostrophe as B) because X11 keycode numbering only
coincidentally overlaps PC/AT scancodes.

Add bidirectional clipboard sync (CF_UNICODETEXT) over the cliprdr channel,
and RDP pointer/cursor shape sync so the local cursor reflects what the
remote OS wants displayed (resize handles, text I-beam, etc.) instead of
staying a static arrow.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/rdp_display_widget.h

@@ -20,6 +20,9 @@ public:
     void setFrame(const QImage& frame);
     void setRemoteDesktopSize(int width, int height);
     void clearFrame();
+    void setCursorImage(const QImage& image, const QPoint& hotspot);
+    void setCursorHidden();
+    void setCursorDefault();
 
 signals:
     void keyInput(int key, quint32 nativeScanCode, const QString& text, bool pressed, int modifiers);
@@ -39,12 +42,22 @@ protected:
     void wheelEvent(QWheelEvent* event) override;
 
 private:
+    enum class CursorMode {
+        Default,
+        Custom,
+        Hidden,
+    };
+
     QImage m_frame;
     QSize m_remoteSize;
+    QImage m_cursorImage;
+    QPoint m_cursorHotspot;
+    CursorMode m_cursorMode;
 
     QRectF renderRect() const;
     QPoint mapToRemote(const QPointF& pos) const;
     QSize effectiveRemoteSize() const;
+    void applyCursor();
 };
 
 #endif