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/session_tab.h

@@ -82,6 +82,7 @@ signals:
     void requestMouseMoveEvent(int x, int y);
     void requestMouseButtonEvent(int x, int y, int button, bool pressed);
     void requestMouseWheelEvent(int x, int y, int deltaX, int deltaY);
+    void requestSetClipboardText(const QString& text);
 
 private slots:
     void onBackendStateChanged(SessionState state, const QString& message);
@@ -89,6 +90,8 @@ private slots:
     void onBackendConnectionError(const QString& displayMessage, const QString& rawMessage);
     void onBackendOutputReceived(const QString& text);
     void onBackendHostKeyConfirmationRequested(const QString& prompt);
+    void onBackendRemoteClipboardTextChanged(const QString& text);
+    void onSystemClipboardChanged();
 
 private:
     Profile m_profile;
@@ -100,6 +103,8 @@ private:
     SessionConnectOptions m_lastConnectOptions;
     QString m_terminalThemeName;
     int m_terminalFontPointSize;
+    QString m_lastSyncedClipboardText;
+    bool m_clipboardSyncSupported;
 
     KodoTerm* m_sshTerminal;
     RdpDisplayWidget* m_rdpDisplay;