docs: sort Prerequisites lists numerically ascending (#100)

Reorder the `## Prerequisites` bullets in 9 modules so prior modules
are listed lowest number first instead of by pedagogical importance or
at random. A trailing "Helpful but not required" group stays last and
is sorted within itself; multi-module bullets sort by their lowest
number. Intro/closing paragraphs are left in place. Prose is unchanged;
only bullet order moves.

Modules touched: 7, 9, 14, 15, 22, 24, 25, 26, 27. The other 18 modules
were already ascending (or have one/zero prereqs) and are untouched.
Module 19's "Helpful but not required: Module 16" correctly trails its
ascending 8/14/18 main list, so it stays as is.

Closes #100

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CamgR4HaVpfaqUViuHUcWw

modules/09-issues-and-the-task-layer/README.md

@@ -8,14 +8,14 @@
 
 ## Prerequisites
 
+- **Module 1**: the `tasks-app` project. The lab writes issues against it.
+- **Module 2**: the repo-as-durable-memory reframe. Issues are the team-scale version of the same
+  idea: shared memory for the work that *hasn't happened yet*.
+- **Module 5**: you committed your AI instructions file. That file plus a good issue is what gives
+  an agent enough context to attempt a task; this module puts that pairing to work.
 - **Module 8**: you have a repo on a remote forge (GitHub or any alternative). Issues live on the
   forge, alongside the code, so this module needs the remote you set up there. Everything here is
   provider-neutral: issues exist on every forge.
-- **Module 5**: you committed your AI instructions file. That file plus a good issue is what gives
-  an agent enough context to attempt a task; this module puts that pairing to work.
-- **Module 2**: the repo-as-durable-memory reframe. Issues are the team-scale version of the same
-  idea: shared memory for the work that *hasn't happened yet*.
-- **Module 1**: the `tasks-app` project. The lab writes issues against it.
 
 You do **not** yet need pull requests (Module 10) or the full collaboration loop (Module 11). This
 module produces the *input* to that loop. We'll point forward to it, not teach it here.