fix(modules-2,6,7,8,9,10,14): deterministic main branch + correct two claims

- M2 lab now `git init -b main` (with older-git fallback note) so every later
  `main` reference resolves; reconciled M3/M6/M7/M8 wording and M10's standalone
  review-lab repo (`git init -qb main`).
- M9: replace "issues are on by default on every forge" with a provider-neutral
  version naming the exceptions (Bitbucket/Azure DevOps/SourceHut).
- M14: qualify "hosted runners need zero setup" — true for SaaS forges; the
  self-hosted track needs a runner attached (Module 19). Both paths stay valid.

Closes #5
Closes #13
Closes #16

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TfzV5QvtPDz8LJS3Pu5VLT

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

@@ -233,8 +233,11 @@ from whichever forge's web form you happen to be filling in.
 
 **You'll need:**
 
-- Your `tasks-app` repo on a forge (Module 8), with issues enabled (they are by default on every
-  forge named in Module 8).
+- Your `tasks-app` repo on a forge (Module 8), with its issue tracker enabled. Most forges turn
+  issues on by default, but not all of them do — consistent with the "the feature set varies" caveat
+  above. Bitbucket Cloud's tracker is off until you enable it, Azure DevOps uses Boards/Work Items
+  rather than an Issues tab, and SourceHut uses a separately provisioned `todo.sr.ht` tracker. If you
+  took the forge-agnostic path, confirm yours has issues available before Part C.
 - The starter files in this module's `lab/` folder:
   - `issue-template.md` — the well-formed-issue skeleton to copy for each issue.
   - `example-issues.md` — three worked issues for `tasks-app`, as a reference/answer key.