Use python3 as the canonical command name course-wide (#104) (#105)

modules/07-worktrees-running-agents-in-parallel/lab/agent-a-prompt.md

@@ -8,8 +8,8 @@ Add a `wipe` command to this task app that removes **all** tasks.
 
 - Put the deletion logic on `TaskList` in `tasks.py` (a `wipe()` method that empties the list),
   and wire a `wipe` command into the dispatch in `cli.py` that calls it and saves.
-- Running `python cli.py wipe` should empty the list and print a short confirmation like
+- Running `python3 cli.py wipe` should empty the list and print a short confirmation like
   `wiped all tasks`.
-- After `wipe`, `python cli.py list` should print `(no tasks yet)`.
+- After `wipe`, `python3 cli.py list` should print `(no tasks yet)`.
 
 Make the change, then stop. I'll review the diff, then have you commit it on this branch.

modules/07-worktrees-running-agents-in-parallel/lab/agent-b-prompt.md

@@ -8,7 +8,7 @@ Add a `remaining` command to this task app that prints how many tasks are still
 
 - Reuse the existing `pending()` method on `TaskList` in `tasks.py`; don't reimplement it.
 - Wire a `remaining` command into the dispatch in `cli.py`.
-- Running `python cli.py remaining` should print something like `2 pending` (the number of tasks not
+- Running `python3 cli.py remaining` should print something like `2 pending` (the number of tasks not
   marked done).
 
 Make the change, then stop. I'll review the diff, then have you commit it on this branch.

modules/07-worktrees-running-agents-in-parallel/lab/start/README.md

@@ -15,11 +15,11 @@ This is the running example for **Module 1** (where you feel the copy-paste prob
 ## Run it
 
 ```bash
-python cli.py add "read module 1"
-python cli.py add "set up my editor"
-python cli.py list
-python cli.py done 0
-python cli.py list
+python3 cli.py add "read module 1"
+python3 cli.py add "set up my editor"
+python3 cli.py list
+python3 cli.py done 0
+python3 cli.py list
 ```
 
 Requires Python 3.10+ (it uses `list[Task]` style type hints). No third-party packages.

modules/07-worktrees-running-agents-in-parallel/lab/start/cli.py

@@ -1,8 +1,8 @@
 """Tiny command-line front end for the demo task app.
 
 Run it:
-    python cli.py add "write the lesson"
-    python cli.py list
+    python3 cli.py add "write the lesson"
+    python3 cli.py list
 
 State is kept in tasks.json next to this file. It's intentionally minimal; the point of this app
 is to be a realistic-but-small thing you change with an AI, not a product.
@@ -31,7 +31,7 @@ def save(tlist: TaskList) -> None:
 def main(argv: list[str]) -> int:
     tlist = load()
     if not argv:
-        print("usage: python cli.py [add <title> | list | done <index> | count | delete <index>]")
+        print("usage: python3 cli.py [add <title> | list | done <index> | count | delete <index>]")
         return 1
 
     command = argv[0]