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/17-secrets-config-and-environments/lab/starter/sync.py

@@ -1,4 +1,4 @@
-"""A 'sync' command for the tasks-app — the BEFORE picture for Module 17.
+"""A 'sync' command for the tasks-app: the BEFORE picture for Module 17.
 
 This is exactly the kind of file an AI hands you when you ask it to "add a command that syncs
 tasks to our backend." It works. It also has two AI-classic mistakes baked in:
@@ -8,7 +8,7 @@ tasks to our backend." It works. It also has two AI-classic mistakes baked in:
      prod at the prod one without editing code.
 
 Your job in the lab is to refactor BOTH out of the source and into the environment. Don't read
-ahead and fix it yet — first run it as-is so you can see the smell.
+ahead and fix it yet; first run it as-is so you can see the smell.
 
 Run it:
     python sync.py