Implement core services for MVP-1 Personal Tracker CLI

Services implemented:
- session_service: Active session management (get/set/clear, validation)
- project_service: Project CRUD and directory structure
- note_service: Note handling and consolidation
- heuristics_service: Rule-based suggestions
- summary_service: Heuristic summary generation

tracker/utils/slug.py

@@ -0,0 +1,13 @@
+"""Slug generation utility."""
+
+
+def generate_slug(name: str) -> str:
+    """Generate a URL-safe slug from a name.
+
+    Args:
+        name: The name to convert to a slug.
+
+    Returns:
+        A lowercase slug with spaces replaced by hyphens.
+    """
+    return name.lower().replace(" ", "-")