Fix broken git demos/labs in Modules 4, 7, 14 (#2,#3,#4,#12) (#55)

Co-authored-by: claude <claude@jpaul.io>
Co-committed-by: claude <claude@jpaul.io>

modules/14-continuous-integration/README.md

@@ -274,15 +274,21 @@ and watch CI stop it.
    `test_pending_excludes_completed_tasks` failed, with the assertion and the actual-vs-expected
    values. CI caught in seconds what a skim would have waved through.
 
-9. Reproduce and fix:
+9. Reproduce and fix. The bad change is already committed *and pushed*, so `git restore` is no help
+   here — it only discards *uncommitted* edits, and there are none. The team-safe undo for something
+   already on shared history is `git revert` (Module 12): it writes a **new** commit that inverts the
+   bad one, instead of rewriting history other people may have pulled.
 
    ```bash
    pytest -q          # fails locally too — same command, same failure
-   git restore tasks.py   # throw away the bad change (Module 2's safety net)
-   git commit -am "Revert: pending() must exclude completed tasks"
-   git push           # CI goes green again
+   git revert HEAD    # new commit that undoes "Simplify pending()" (Module 12)
+   git push           # CI re-runs on the fixed code and goes green again
    ```
 
+   `git revert HEAD` opens an editor with a prefilled message (`Revert "Simplify pending()"`) — save
+   and close it. The revert restores the correct `pending()`, the push triggers CI on the fixed code,
+   and the run goes green.
+
 10. *(Optional, to feel the linter tier.)* Add an obviously unused import to `cli.py`
     (`import os` at the top, unused), commit, and push. Watch the **Lint** step fail *before* the
     tests even run — the cheap check failing fast. Remove it and push again.