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/24-assistive-agents/lab/sample-issue.md

@@ -1,6 +1,6 @@
 Title: `done` command crashes on an empty list
 
-When I run `python cli.py done 0` right after a fresh checkout — before adding any tasks — it throws
+When I run `python cli.py done 0` right after a fresh checkout, before adding any tasks, it throws
 an IndexError and dumps a stack trace instead of a friendly message. Every other command handles the
 empty-list case fine, so this one feels like an oversight.