feat(todo): add numbered tasks, edit, done, and future filtering

Implement smoother todo editing with the following features:
- Display numbered tasks [1], [2], etc. in `streamd todo`
- Add `streamd todo N edit` to open editor at task line
- Add `streamd todo N done` to insert @Done after @Task
- Add `--show-future` flag to include future tasks (hidden by default)

src/cli/mod.rs

@@ -1,4 +1,4 @@
 pub mod args;
 pub mod commands;
 
-pub use args::{Cli, Commands};
+pub use args::{Cli, Commands, TodoAction};