Implement CLI commands and utility functions for MVP-1

- Add complete CLI command implementations with Typer subcommands
- Implement utils/time.py with duration formatting and datetime utilities
- Implement utils/path.py with project path management utilities
- Wire up all commands to main CLI entry point

tracker/cli/main.py

@@ -1,7 +1,42 @@
 """Main CLI entry point."""
+
 import typer
 
+from tracker.cli.commands import (
+    init_project,
+    list_projects,
+    show_project,
+    start_session,
+    add_note_cmd,
+    stop_session,
+    add_change,
+    suggest_next,
+    review,
+)
+
 app = typer.Typer(
     name="tracker",
-    help="Personal project tracker CLI",
+    help="Personal Project Tracker CLI - Track your projects with Markdown and YAML",
 )
+
+
+# Register all subcommands
+app.add_typer_command(init_project, name="init-project")
+app.add_typer_command(list_projects, name="list")
+app.add_typer_command(show_project, name="show")
+app.add_typer_command(start_session, name="start")
+app.add_typer_command(add_note_cmd, name="note")
+app.add_typer_command(stop_session, name="stop")
+app.add_typer_command(add_change, name="change")
+app.add_typer_command(suggest_next, name="next")
+app.add_typer_command(review, name="review")
+
+
+@app.callback()
+def callback():
+    """Personal Project Tracker - Track your projects locally with Markdown."""
+    pass
+
+
+if __name__ == "__main__":
+    app()