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

modules/23-working-with-existing-codebases/lab/orient.py

@@ -12,8 +12,8 @@ then verifies and deepens this; you never let it map from vibes alone.
 
 No dependencies. Standard library only. Works on any OS with Python 3.10+ and git.
 
-    python orient.py                 # print the pack
-    python orient.py > ORIENT.md     # save it to hand to the AI (don't commit it)
+    python3 orient.py                 # print the pack
+    python3 orient.py > ORIENT.md     # save it to hand to the AI (don't commit it)
 """
 
 from __future__ import annotations
@@ -61,7 +61,7 @@ SIGNALS: dict[str, str] = {
 
 # Common test-runner hints keyed off a present signal file.
 TEST_HINTS: dict[str, str] = {
-    "pyproject.toml": "pytest    (or: python -m pytest)",
+    "pyproject.toml": "pytest    (or: python3 -m pytest)",
     "tox.ini": "tox",
     "package.json": "npm test    (check the \"scripts\" block for the real command)",
     "go.mod": "go test ./...",