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/16-containers-and-reproducible-environments/lab/dockerignore-starter

@@ -4,19 +4,19 @@
 # bloat the image, slow the build, or leak into it. A lean, predictable build context is part of
 # what makes the image reproducible.
 
-# Python caches — regenerated, never shipped
+# Python caches: regenerated, never shipped
 __pycache__/
 *.pyc
 
-# Runtime state — never bake one machine's data into a shared image
+# Runtime state: never bake one machine's data into a shared image
 tasks.json
 
-# Version control and project meta — not needed to run the app
+# Version control and project meta: not needed to run the app
 .git/
 .gitignore
 .dockerignore
 
-# Local environments and docs — keep them out of the image
+# Local environments and docs: keep them out of the image
 .venv/
 venv/
 *.md