Improve TDD skill guidance and add frontend visual polish step

[codingarchitect-wq]

Summary

• Add "What NOT to Test" section to TDD skill — prevents wasting budget on static markup, CSS classes, element counts, and pure presentational components
• Refine coverage target from "80%+ Coverage" to "80%+ Coverage of Logic Paths" (branch/logic coverage, not line coverage of markup)
• Update verification checklist to only require tests for functions with logic (conditionals, computation, side effects)
• Add Step 4b "Frontend Visual Polish" to implement-feature skill — ensures UI tasks get visual variety before handoff

Motivation

In my eval runs, ~41% of generated tests were testing static markup (CSS classes, element counts, SVG rendering) rather than actual behavior. These tests waste context budget, create maintenance burden, and only fail on intentional UI changes — not bugs. The coverage target and checklist changes reinforce that testing effort should focus on logic paths.

[etr]

Thanks! These both will be very helpful.