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/utils/path.py

@@ -1 +1,87 @@
 """Path utility functions."""
+
+from pathlib import Path
+from typing import Optional
+
+
+def ensure_dir(path: Path) -> Path:
+    """Ensure a directory exists, creating it if necessary.
+
+    Args:
+        path: Path to the directory.
+
+    Returns:
+        The path to the directory.
+    """
+    path.mkdir(parents=True, exist_ok=True)
+    return path
+
+
+def project_root(slug: str, projects_root: Optional[Path] = None) -> Path:
+    """Get the root path for a project.
+
+    Args:
+        slug: Project slug.
+        projects_root: Root directory for all projects. Defaults to ./projects.
+
+    Returns:
+        Path to the project root.
+    """
+    if projects_root is None:
+        projects_root = Path("projects")
+    return projects_root / slug
+
+
+def relative_to_project(slug: str, relative_path: str, projects_root: Optional[Path] = None) -> Path:
+    """Get a path relative to a project.
+
+    Args:
+        slug: Project slug.
+        relative_path: Relative path within the project.
+        projects_root: Root directory for all projects.
+
+    Returns:
+        Absolute path to the file within the project.
+    """
+    root = project_root(slug, projects_root)
+    return root / relative_path
+
+
+def is_within_project(slug: str, file_path: Path, projects_root: Optional[Path] = None) -> bool:
+    """Check if a file path is within a project.
+
+    Args:
+        slug: Project slug.
+        file_path: Path to check.
+        projects_root: Root directory for all projects.
+
+    Returns:
+        True if file_path is within the project directory.
+    """
+    project_path = project_root(slug, projects_root)
+    try:
+        file_path.resolve().relative_to(project_path.resolve())
+        return True
+    except ValueError:
+        return False
+
+
+def sanitize_filename(filename: str) -> str:
+    """Sanitize a filename by removing invalid characters.
+
+    Args:
+        filename: Original filename.
+
+    Returns:
+        Sanitized filename safe for file system use.
+    """
+    # Remove or replace invalid characters
+    invalid_chars = '<>:"/\\|?*'
+    for char in invalid_chars:
+        filename = filename.replace(char, "_")
+
+    # Limit length
+    if len(filename) > 255:
+        filename = filename[:255]
+
+    return filename

tracker/utils/time.py

@@ -1 +1,91 @@
 """Time utility functions."""
+
+from datetime import datetime, timedelta
+
+
+def format_duration(minutes: int) -> str:
+    """Format duration in minutes to human-readable string.
+
+    Args:
+        minutes: Duration in minutes.
+
+    Returns:
+        Human-readable duration string (e.g., "1h 30m", "45m").
+    """
+    if minutes < 60:
+        return f"{minutes}m"
+    hours = minutes // 60
+    remaining_minutes = minutes % 60
+    if remaining_minutes == 0:
+        return f"{hours}h"
+    return f"{hours}h {remaining_minutes}m"
+
+
+def parse_duration(duration_str: str) -> int:
+    """Parse duration string to minutes.
+
+    Args:
+        duration_str: Duration string like "1h 30m", "45m", "2h".
+
+    Returns:
+        Duration in minutes.
+    """
+    total_minutes = 0
+    duration_str = duration_str.lower().strip()
+
+    # Parse hours
+    if "h" in duration_str:
+        parts = duration_str.split()
+        for part in parts:
+            if "h" in part:
+                total_minutes += int(part.replace("h", "")) * 60
+            elif "m" in part:
+                total_minutes += int(part.replace("m", ""))
+
+    # If no hours, try just minutes
+    if total_minutes == 0 and "m" in duration_str:
+        total_minutes = int(duration_str.replace("m", ""))
+    elif total_minutes == 0:
+        try:
+            total_minutes = int(duration_str)
+        except ValueError:
+            return 0
+
+    return total_minutes
+
+
+def is_recent(dt: datetime, hours: int = 24) -> bool:
+    """Check if a datetime is within the specified hours.
+
+    Args:
+        dt: Datetime to check.
+        hours: Number of hours to consider as "recent".
+
+    Returns:
+        True if dt is within the specified hours.
+    """
+    return datetime.now() - dt < timedelta(hours=hours)
+
+
+def format_datetime(dt: datetime) -> str:
+    """Format datetime to standard string.
+
+    Args:
+        dt: Datetime to format.
+
+    Returns:
+        Formatted string in YYYY-MM-DD HH:MM format.
+    """
+    return dt.strftime("%Y-%m-%d %H:%M")
+
+
+def format_date(dt: datetime) -> str:
+    """Format datetime to date string.
+
+    Args:
+        dt: Datetime to format.
+
+    Returns:
+        Formatted string in YYYY-MM-DD format.
+    """
+    return dt.strftime("%Y-%m-%d")