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_session_backend.h

@@ -34,6 +34,7 @@ public slots:
     void sendMouseMoveEvent(int x, int y) override;
     void sendMouseButtonEvent(int x, int y, int button, bool pressed) override;
     void sendMouseWheelEvent(int x, int y, int deltaX, int deltaY) override;
+    void setClipboardText(const QString& text) override;
 
 private:
     enum class InputEventType {
@@ -42,6 +43,7 @@ private:
         MouseButton,
         MouseWheel,
         Resize,
+        SetClipboardText,
     };
 
     struct InputEvent {
@@ -84,6 +86,10 @@ private:
     int m_lastResizeWidth;
     int m_lastResizeHeight;
 
+    std::mutex m_cliprdrMutex;
+    void* m_cliprdrContext;
+    QString m_pendingLocalClipboardText;
+
     void setState(SessionState state, const QString& message);
     bool validateProfile(QString& message) const;
     void startWorker();
@@ -92,12 +98,17 @@ private:
     void enqueueInputEvent(const InputEvent& event);
     void processInputEvents(rdp_freerdp* instance);
     bool sendDisplayResize(rdp_freerdp* instance, int width, int height);
+    void sendClipboardTextToRemote(rdp_freerdp* instance, const QString& text);
 public:
     void onChannelConnectedEvent(const char* name, void* channelInterface);
     void onChannelDisconnectedEvent(const char* name, void* channelInterface);
     void onDisplayControlCaps(uint32_t maxNumMonitors,
                               uint32_t maxMonitorAreaFactorA,
                               uint32_t maxMonitorAreaFactorB);
+    void onCliprdrMonitorReady();
+    void onCliprdrServerFormatList(bool hasUnicodeText);
+    void onCliprdrServerFormatDataRequest(uint32_t requestedFormatId);
+    void onCliprdrServerFormatDataResponse(bool success, const uint8_t* data, uint32_t size);
 private:
     void emitStateAsync(SessionState state, const QString& message);
     void emitConnectionFailureAsync(const QString& displayMessage, const QString& rawMessage);