feat: Implement core functionality for DTC C/C++ IDE

- Added ProjectManager class to handle project operations including opening, closing, building, and running projects.
- Introduced SyntaxHighlighter class for syntax highlighting in C and C++ files.
- Developed TerminalWidget for command execution and output display.
- Created TextEditor with line numbering and auto-indentation features.
- Established main application entry point in main.cpp.
- Designed UI layout for MainWindow using Qt Designer.

include/TerminalWidget.h

@@ -0,0 +1,58 @@
+#pragma once
+
+#include <QtWidgets/QWidget>
+#include <QtWidgets/QTextEdit>
+#include <QtWidgets/QLineEdit>
+#include <QtWidgets/QVBoxLayout>
+#include <QtWidgets/QHBoxLayout>
+#include <QtWidgets/QPushButton>
+#include <QtCore/QProcess>
+#include <QtCore/QTimer>
+
+class TerminalWidget : public QWidget
+{
+    Q_OBJECT
+
+public:
+    explicit TerminalWidget(QWidget *parent = nullptr);
+    ~TerminalWidget();
+
+    void setWorkingDirectory(const QString &directory);
+    QString workingDirectory() const;
+    
+    void executeCommand(const QString &command);
+    void clear();
+    
+    void showBuildOutput();
+    void showRunOutput();
+
+signals:
+    void commandFinished(int exitCode);
+
+private slots:
+    void onCommandEntered();
+    void onProcessFinished(int exitCode, QProcess::ExitStatus exitStatus);
+    void onProcessError(QProcess::ProcessError error);
+    void onProcessOutput();
+    void updatePrompt();
+
+private:
+    void setupUI();
+    void setupProcess();
+    void appendOutput(const QString &text, const QColor &color = Qt::white);
+    void appendPrompt();
+
+    QTextEdit *m_output;
+    QLineEdit *m_input;
+    QPushButton *m_clearButton;
+    
+    QProcess *m_process;
+    QString m_workingDirectory;
+    QString m_currentPrompt;
+    
+    // Colors for different output types
+    QColor m_normalColor;
+    QColor m_errorColor;
+    QColor m_successColor;
+    QColor m_promptColor;
+};