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/02-version-control-as-a-safety-net/lab/gitignore-starter

@@ -0,0 +1,16 @@
+# Copy this to a file named exactly ".gitignore" in your project root.
+#
+# A .gitignore tells Git which files to leave untracked. The rule of thumb: version the things a
+# human (or AI) authors, ignore the things a machine generates. For our tasks-app:
+
+# Runtime state — generated by running the app, not authored. Not something you want in history.
+tasks.json
+
+# Python bytecode caches — generated, never edited by hand.
+__pycache__/
+*.pyc
+
+# Editor / OS noise that doesn't belong to the project.
+.vscode/
+.idea/
+.DS_Store