refactor: modularize CLI and optimize cache metadata lookups

- Extract error handling, path validation, and handlers into separate modules
- Add CacheCheckResult to pre-fetch metadata and avoid double lookups
- Deprecate legacy cache methods in favor of optimized alternatives
- Enable tokio fs feature for async file operations
- Remove debug profile from release build

src/main.rs

@@ -1,8 +1,5 @@
 use clap::Parser;
-use noentropy::cli::{
-    Args,
-    orchestrator::{handle_organization, handle_undo},
-};
+use noentropy::cli::{Args, handle_organization, handle_undo};
 use noentropy::settings::config::change_and_prompt_api_key;
 use noentropy::settings::{get_or_prompt_config, get_or_prompt_download_folder};