style(no-slop): remove every em-dash + banned words across all modules + capstone

Apply the no-ai-slop standard (now binding in AGENTS.md): the em-dash character is
banned outright (restructured, not blind-replaced), plus the banned word/phrase
list (delve, leverage, robust, seamless, truly, unlock, etc.). 0 em-dashes remain
in modules + capstone; the only "robust" left is the planted M10 ai-change.patch
trap. Module H1 titles use a colon separator.

All deliberate teaching devices preserved; labs compile/parse (py/sh/yaml/json);
no junk. AGENTS.md updated with the hard no-slop rules.

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

modules/11-collaboration-humans-and-agents/lab/pr-body.md

@@ -1,5 +1,5 @@
 <!--
-  Module 11 lab — the pull request description (station 4 of the loop).
+  Module 11 lab: the pull request description (station 4 of the loop).
 
   Paste this as the body when you open the PR from your branch into main. The "Closes" line is the
   load-bearing part: replace 42 with YOUR issue number. On merge to the default branch, the host
@@ -18,7 +18,7 @@ method in `tasks.py`; `cli.py` just wires up the command and reports how many ta
 
 - Added a mix of pending and done tasks, ran `clear-done`, confirmed only the done ones were removed
   and the count printed.
-- Ran `clear-done` with nothing marked done — removed 0, no crash.
+- Ran `clear-done` with nothing marked done: removed 0, no crash.
 
 ## Review notes