FIX: remove task link on drop

.tsk/archive/tsk-28.tsk

···
+Add tool to clean up old tasks not in index
+
+Previously the `drop` command did not remove the symlink in .tsk/tasks when a
+task was dropped, only removing it from the index. I don't recall if this was
+because my original design expected the index to be the source of truth on
+whether a task was prioritized or not or if I simply forgot to add it. Either
+way, drop now properly removes the symlink but basically every existing
+workspace has a bunch of junk in it. I can write a simple script that deletes
+all symlinks that aren't present in the index.
+
+This does suggest that I should add a reindex command to add tasks that are not
+present in the index but are in the tasks folder to the index at the *bottom*,
+preserving the existing order of the index.

.tsk/index

···
-tsk-27	Fix -F doc on find	1732997985
+tsk-28	Add tool to clean up old tasks not in index	1733166288
 tsk-10	foreign workspaces	1732594198
 tsk-21	Add command to setup git stuff	1732594198
 tsk-8	IMAP4-based sync	1732594198

.tsk/next

···
-28
+29

.tsk/tasks/tsk-28.tsk

···
+../archive/tsk-28.tsk

Cargo.lock

···
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-version = 3
+version = 4
 
 [[package]]
 name = "anstream"
···
 
 [[package]]
 name = "tsk-cli"
-version = "0.2.4"
+version = "0.2.5"
 dependencies = [
  "clap",
  "clap_complete",

src/workspace.rs

···
 use std::collections::{vec_deque, BTreeMap, HashSet};
 use std::ffi::OsString;
 use std::fmt::Display;
-use std::fs::File;
+use std::fs::{remove_file, File};
 use std::io::{BufRead as _, BufReader, Read, Seek, SeekFrom};
 use std::ops::Deref;
 use std::os::unix::fs::symlink;
···
         let id = self.resolve(identifier)?;
         let mut stack = self.read_stack()?;
         let index = &stack.iter().map(|i| i.id).position(|i| i == id);
+        // TODO: remove the softlink in .tsk/tasks
         let task = if let Some(index) = index {
             let prioritized_task = stack.remove(*index);
             stack.save()?;
···
         } else {
             None
         };
+        remove_file(self.path.join("tasks").join(format!("tsk-{}.tsk", id)))?;
         Ok(task)
     }