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/ProjectManager.h

@@ -0,0 +1,66 @@
+#pragma once
+
+#include <QtCore/QObject>
+#include <QtCore/QString>
+#include <QtCore/QDir>
+#include <QtCore/QFileInfo>
+#include <QtCore/QProcess>
+
+class ProjectManager : public QObject
+{
+    Q_OBJECT
+
+public:
+    explicit ProjectManager(QObject *parent = nullptr);
+    ~ProjectManager();
+
+    bool openProject(const QString &projectPath);
+    void closeProject();
+    
+    QString projectPath() const;
+    QString projectName() const;
+    bool hasProject() const;
+    
+    bool isCMakeProject() const;
+    bool isQMakeProject() const;
+    
+    void buildProject();
+    void cleanProject();
+    void configureProject();
+    void runProject();
+    
+    QString buildDirectory() const;
+    QString sourceDirectory() const;
+
+signals:
+    void projectOpened(const QString &projectPath);
+    void projectClosed();
+    void buildStarted();
+    void buildFinished(bool success);
+    void buildOutput(const QString &output);
+
+private slots:
+    void onBuildProcessFinished(int exitCode, QProcess::ExitStatus exitStatus);
+    void onBuildProcessError(QProcess::ProcessError error);
+    void onBuildOutput();
+
+private:
+    void detectProjectType();
+    void setupBuildDirectory();
+    QString findCMakeListsFile(const QString &directory) const;
+    QString findQMakeFile(const QString &directory) const;
+
+    QString m_projectPath;
+    QString m_projectName;
+    QString m_buildDirectory;
+    
+    enum ProjectType {
+        Unknown,
+        CMake,
+        QMake
+    };
+    ProjectType m_projectType;
+    
+    QProcess *m_buildProcess;
+    bool m_isBuilding;
+};