Enhance project structure and add new files for enrichment and analysis

- Updated AGENTS.md to reflect changes in CLI commands and module organization, including the addition of an enrichment step and new functional modules.
- Introduced analysis.json, identities.json, inventory.csv, and plan.json to support enriched metadata and execution planning.
- Added CODE_IMPROVEMENTS.md to document identified code issues and proposed solutions for future enhancements.
- Updated README.md to include new enrichment features and configuration options.
- Removed unused dependency on ffmpeg-python from pyproject.toml.

These changes improve the overall functionality and maintainability of the Video Library Manager project.

src/vlm/utils.py

@@ -0,0 +1,24 @@
+"""Shared utilities for Video Library Manager."""
+
+from datetime import datetime, timezone
+
+
+def utc_now() -> datetime:
+    """Return current UTC time (timezone-aware)."""
+    return datetime.now(timezone.utc)
+
+
+def ensure_utc(dt: datetime) -> datetime:
+    """Ensure datetime is timezone-aware UTC (for backward compatibility with naive ISO strings)."""
+    if dt.tzinfo is None:
+        return dt.replace(tzinfo=timezone.utc)
+    return dt.astimezone(timezone.utc)
+
+
+def format_size(size_bytes: int) -> str:
+    """Format file size in human-readable format (e.g. 1.5 GB, 234.2 MB)."""
+    for unit in ["B", "KB", "MB", "GB", "TB"]:
+        if size_bytes < 1024.0:
+            return f"{size_bytes:.1f} {unit}"
+        size_bytes /= 1024.0
+    return f"{size_bytes:.1f} PB"