Break up task_discovery

dev_docs/project_plan.md

@@ -25,6 +25,7 @@ This plan outlines the major development phases and tasks for building `dela`, a
   - [x] [DTKT-6] Implement parser for `pyproject.toml` scripts (`pyproject-toml`).
   - [x] [DTKT-106] For `package.json`, detect if there is a lock file `pnpm` or  `npm` or `yarn` or `bun` use that to run tasks.
   - [x] [DTKT-104] Update makefile-lossless to new version supporting trailing text.
+  - [x] [DTKT-200] Refactor `src/task_discovery.rs` into a registry-based `TaskDiscovery` trait with per-runner modules under `src/task_discovery/`.
 
 - [ ] **Structs and Runners**
   - [x] [DTKT-7] Define `Task` and `TaskRunner` enums in `types.rs`.

src/commands/list.rs

@@ -290,8 +290,8 @@ pub fn execute(verbose: bool) -> Result<(), String> {
                     used_footnotes.insert('‖', true);
                 }
 
-                if task.shadowed_by.is_some() {
-                    match task.shadowed_by.as_ref().unwrap() {
+                if let Some(shadowed_by) = &task.shadowed_by {
+                    match shadowed_by {
                         ShadowType::ShellBuiltin(_) => {
                             used_footnotes.insert('†', true);
                         }