fix(running-example): consistent lab-script paths, tasks.json policy, no command collisions

- Lab-script path convention: course scripts live in modules/NN/lab/; copy the
  one a step needs into tasks-app, then run by bare name (M4/M6/M7/M26 + headers).
- tasks.json stays gitignored: M20 verifies via `cli.py list`/`cat tasks.json`
  (not git diff) and frames runtime state as deliberately ignored; M22 cleanup
  uses `rm tasks.json`; M10 review-lab gets its own .gitignore.
  Module 21's lab deliberately ships NO .gitignore (teaching device) — untouched.
- Stop running-example command collisions: M5 clear->search, M6 count/clear->
  stats/purge, M7 clear/count->wipe/remaining (README + scripts + agent prompts +
  branch/worktree names). M6 conflict still reproduces on the carried usage line.

Closes #7
Closes #10
Closes #11

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TfzV5QvtPDz8LJS3Pu5VLT

modules/07-worktrees-running-agents-in-parallel/lab/setup-worktrees.sh

@@ -1,15 +1,16 @@
 #!/usr/bin/env bash
 #
 # Module 7 lab — create two linked worktrees off the tasks-app repo, each on its own branch.
-# Run this from INSIDE your tasks-app repo (the one you git-init'd in Module 2):
+# Copy this into your tasks-app repo (the one you git-init'd in Module 2), then run it from inside:
 #
-#     bash modules/07-worktrees-running-agents-in-parallel/lab/setup-worktrees.sh
+#     cp /path/to/modules/07-worktrees-running-agents-in-parallel/lab/setup-worktrees.sh .
+#     bash setup-worktrees.sh
 #
 # It places the new worktree folders next to the repo, so you end up with:
 #
-#     <parent>/tasks-app          (your existing repo, on its current branch)
-#     <parent>/tasks-app-clear    (new worktree on branch feature/clear)
-#     <parent>/tasks-app-count    (new worktree on branch feature/count)
+#     <parent>/tasks-app              (your existing repo, on its current branch)
+#     <parent>/tasks-app-wipe         (new worktree on branch feature/wipe)
+#     <parent>/tasks-app-remaining    (new worktree on branch feature/remaining)
 #
 set -euo pipefail
 
@@ -17,8 +18,8 @@ set -euo pipefail
 ROOT="$(git rev-parse --show-toplevel)"
 PARENT="$(cd "$ROOT/.." && pwd)"
 
-git worktree add "$PARENT/tasks-app-clear" -b feature/clear
-git worktree add "$PARENT/tasks-app-count" -b feature/count
+git worktree add "$PARENT/tasks-app-wipe" -b feature/wipe
+git worktree add "$PARENT/tasks-app-remaining" -b feature/remaining
 
 echo
 echo "Worktrees created. One repo, three checked-out branches:"