Reflow chapters: tables and bullets over paragraph enumerations

[sanketsudake]

Apply the scannability style from the agentic-engineering worksheet:
lists and tables replace paragraph-shaped enumerations.

Style contract (STYLE.md)

• Failure bullets are nested:
  each **Symptom:** bullet carries indented **Cause:** and **Where to look:** sub-bullets
  (4-space indents, because python-markdown flattens 2-space ones).
• New rule "Lists for parallel items":
  a paragraph that enumerates parallel items keeps its lead-in as prose
  and puts each item on a bullet with a bold lead term;
  a table is used when the items share attributes.

Chapters

• All 126 failure bullets across the chapters use the nested shape.
• Enumeration reflow (prose runs into bullets, numbered lists, and small tables)
  lands as a follow-up commit on this branch — survey in progress.

Verification

• Every figure caption still couples to its mermaid fence
  (checked with the build's own regex).