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/planner.py

@@ -11,6 +11,7 @@ from pathlib import Path
 from typing import Union
 
 from vlm.config import Config
+from vlm.utils import ensure_utc, utc_now
 from vlm.models import (
     ExecutionPlan,
     FileOperation,
@@ -48,7 +49,7 @@ def generate_plan(
     
     return ExecutionPlan(
         plan_id=str(uuid.uuid4()),
-        created_at=datetime.now(),
+        created_at=utc_now(),
         operations=operations,
         summary=summary
     )
@@ -391,10 +392,11 @@ def load_plan(input_path: Path) -> ExecutionPlan:
         for op in plan_dict["operations"]
     ]
     
-    # Reconstruct ExecutionPlan
+    # Reconstruct ExecutionPlan (normalize naive datetime to UTC for backward compatibility)
+    created_at = ensure_utc(datetime.fromisoformat(plan_dict["created_at"]))
     return ExecutionPlan(
         plan_id=plan_dict["plan_id"],
-        created_at=datetime.fromisoformat(plan_dict["created_at"]),
+        created_at=created_at,
         operations=operations,
         summary=plan_dict["summary"]
     )