Refactor configuration management and remove deprecated files

- Consolidated database, file source, and field mapping configurations into dedicated modules under the `config` directory.
- Removed hardcoded database connection details from `migration.py` and replaced them with imports from the new configuration structure.
- Updated `ntfy_utils.py` and `run_incremental_sync.py` to utilize the new configuration imports for cleaner code and better maintainability.
- Deleted `update_config.py` as its contents have been integrated into the new configuration files.
- Added a new `settings.local.json` for managing permissions related to script execution.
- Enhanced the structure of the migration tasks and Excel configurations for better organization and clarity.

.claude/settings.local.json

@@ -0,0 +1,13 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(python etl_manager.py --help)",
+      "Bash(python run_incremental_sync.py)",
+      "Bash(python -c \"import run_incremental_sync; print\\(''run_incremental_sync.py: import OK''\\)\")",
+      "Bash(python -c \"import etl_manager; print\\(''etl_manager.py: import OK''\\)\")",
+      "Bash(python -c \"import init_full_sync; print\\(''init_full_sync.py: import OK''\\)\")",
+      "Bash(python -c \"import migration; print\\(''migration.py: import OK''\\)\")",
+      "Bash(python migration.py)"
+    ]
+  }
+}