Session UX: inline password prompt and terminal font size controls

Replace the modal RDP/SSH password dialog with an inline prompt bar
embedded in the session tab instead of a separate popup window. Add
per-tab terminal font size controls (increase/decrease/reset/set
exact point size) via the tab context menu, with the chosen size
persisted across sessions.

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

src/terminal_view.h

@@ -19,6 +19,7 @@ public:
     static QStringList themeNames();
     void setThemeName(const QString& themeName);
     void appendTerminalData(const QString& data);
+    void setFontPointSize(int pointSize);
 
 signals:
     void inputGenerated(const QString& input);