Revise /beautiful_deck and /tikz as a shared deck-quality workflow

[nsmiller2501]

Summary

This PR updates the deck-generation stack around /beautiful_deck and /tikz, with /tikz owning the shared measurement rule book and /beautiful_deck using it upstream to prevent collisions before repair is needed.

What changed

• Makes audience resolution a required first step for /beautiful_deck.
• Adds deck rhetoric reference files, style preferences, palettes, domain patterns, and a house-style preamble.
• Clarifies that the house-style preamble is opt-in and should not anchor original audience-specific designs.
• Strengthens title-line, microtext, image-placeholder, and Beamer layout guidance.
• Moves TikZ collision formulas into /tikz/tikz_rules.md as the shared rule book.
• Refactors /tikz into an operational checklist that reads the rule book before auditing.
• Updates public docs for the new prevention-first flow: /beautiful_deck Step 4.4 prevents common collisions; /tikz audits residual issues.

Why

The main goal is to make generated decks more reliable before the compile/audit loop begins. In beta use, most TikZ problems were easier to prevent during generation than repair after the fact.

Testing

• Reviewed the branch diff against the PR notes.
• Checked for stale references to the old compiledeck-owned TikZ rule book and updated the public docs accordingly.
• No automated tests were run; this is a skill/documentation protocol update.