feat(course): build out all 27 modules, capstone, scaffold, and conventions

Scaffold the course repo and author the full curriculum in dependency-chain
order, following the settled build decisions in handoff.md.

- Scaffold: course README, vendor-neutral AGENTS.md (dogfoods Module 5),
  _TEMPLATE.md (the fixed 9-section module shape), root .gitignore, ship config.
- Modules 1-2: reference exemplars (locked for tone/depth/lab style).
- Modules 3-27: full lessons + runnable labs, each following the template,
  respecting the chain, vendor/model-agnostic, with "feel the pain" labs.
- Module 8 hosting comparison web-researched and date-stamped (as of 2026-06-22),
  not written from memory; expansion-zone modules carry Verify-before-publish.
- Capstone: the full loop end to end on the running tasks-app example.

Lab code syntax-checked (Python/shell/YAML); every module has the 7 core
template sections.

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/agent-a-prompt.md

@@ -0,0 +1,15 @@
+# Agent A prompt — the `clear` command
+
+Paste this into the AI session you've pointed at the `tasks-app-clear` worktree folder.
+
+---
+
+Add a `clear` command to this task app that removes **all** tasks.
+
+- Put the deletion logic on `TaskList` in `tasks.py` (a `clear()` method that empties the list),
+  and wire a `clear` command into the dispatch in `cli.py` that calls it and saves.
+- Running `python cli.py clear` should empty the list and print a short confirmation like
+  `cleared all tasks`.
+- After `clear`, `python cli.py list` should print `(no tasks yet)`.
+
+Make the change, then stop — I'll review the diff and commit it myself.

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

@@ -0,0 +1,14 @@
+# Agent B prompt — the `count` command
+
+Paste this into the AI session you've pointed at the `tasks-app-count` worktree folder.
+
+---
+
+Add a `count` command to this task app that prints how many tasks are still pending.
+
+- Reuse the existing `pending()` method on `TaskList` in `tasks.py`; don't reimplement it.
+- Wire a `count` command into the dispatch in `cli.py`.
+- Running `python cli.py count` should print something like `2 pending` (the number of tasks not
+  marked done).
+
+Make the change, then stop — I'll review the diff and commit it myself.

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

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+#
+# Module 7 lab — tear down the two worktrees created by setup-worktrees.sh.
+# Run from INSIDE your tasks-app repo:
+#
+#     bash modules/07-worktrees-running-agents-in-parallel/lab/cleanup-worktrees.sh
+#
+# `git worktree remove` deletes the folder AND clears Git's record of it; `prune` mops up any
+# worktrees whose folders were deleted by hand (which leaves a stale record otherwise).
+#
+# NOTE: --force discards UNCOMMITTED work in a worktree. Commit (or merge) before cleaning up.
+# This script assumes you already merged feature/clear and feature/count back into main.
+#
+set -euo pipefail
+
+ROOT="$(git rev-parse --show-toplevel)"
+PARENT="$(cd "$ROOT/.." && pwd)"
+
+git worktree remove "$PARENT/tasks-app-clear" --force 2>/dev/null || true
+git worktree remove "$PARENT/tasks-app-count" --force 2>/dev/null || true
+git worktree prune
+
+echo
+echo "Cleanup done. Remaining worktrees:"
+git worktree list
+
+echo
+echo "If you merged both branches you can also delete them:"
+echo "    git branch -d feature/clear feature/count"

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

@@ -0,0 +1,25 @@
+#!/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):
+#
+#     bash modules/07-worktrees-running-agents-in-parallel/lab/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)
+#
+set -euo pipefail
+
+# The directory that contains the repo, so the new worktrees become siblings of it.
+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
+
+echo
+echo "Worktrees created. One repo, three checked-out branches:"
+git worktree list