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/27-evals/lab/candidates/swapped_model/tasks.py

@@ -0,0 +1,50 @@
+"""Candidate output: a SWAPPED model/prompt.
+
+Same task, different model (or a tweaked prompt). This output "looks right" and
+passes a casual manual check — adding three tasks and calling count returns 3.
+But pending_count() returns the total number of tasks, not the number of
+*pending* ones, so it's wrong the moment anything is marked done.
+
+Nobody would notice this by skimming. The eval set notices it instantly. That's
+the regression eval catching an unsafe swap — exactly the scenario this module
+exists for. Replace this with your own swapped-model output when you run it for
+real; you may get lucky and have it pass, or you may catch a regression like
+this one.
+"""
+
+from dataclasses import dataclass, field
+
+
+@dataclass
+class Task:
+    title: str
+    done: bool = False
+
+
+@dataclass
+class TaskList:
+    tasks: list[Task] = field(default_factory=list)
+
+    def add(self, title: str) -> Task:
+        task = Task(title=title)
+        self.tasks.append(task)
+        return task
+
+    def complete(self, index: int) -> None:
+        self.tasks[index].done = True
+
+    def pending(self) -> list[Task]:
+        return [t for t in self.tasks if not t.done]
+
+    def pending_count(self) -> int:
+        # WRONG, but plausibly so: counts every task, not just pending ones.
+        return len(self.tasks)
+
+    def render(self) -> str:
+        if not self.tasks:
+            return "(no tasks yet)"
+        lines = []
+        for i, task in enumerate(self.tasks):
+            box = "[x]" if task.done else "[ ]"
+            lines.append(f"{i}. {box} {task.title}")
+        return "\n".join(lines)