feat: /design-consultation — risk-taking thesis, visual research, ambitious preview

Add SAFE/RISK breakdown to design proposals so users see which choices
match category conventions vs. which are deliberate creative departures.

Wire browse binary for visual competitive research — agent browses
competitor sites, takes screenshots, and analyzes fonts/colors/spacing
with graceful degradation to WebSearch-only or built-in knowledge.

Upgrade preview page instructions to render realistic product mockups
(dashboards, marketing pages, settings forms) instead of just swatches.

Rewrite README section with the thesis: "coherence is table stakes —
the real question is where you take risks."

qa-only/SKILL.md.tmpl

@@ -52,7 +52,7 @@ Before falling back to git diff heuristics, check for richer test plan sources:
 
 1. **Project-scoped test plans:** Check `~/.gstack/projects/` for recent `*-test-plan-*.md` files for this repo
    ```bash
-   SLUG=$(git remote get-url origin 2>/dev/null | sed 's|.*[:/]\([^/]*/[^/]*\)\.git$|\1|;s|.*[:/]\([^/]*/[^/]*\)$|\1|' | tr '/' '-')
+   eval $(~/.claude/skills/gstack/bin/gstack-slug 2>/dev/null)
    ls -t ~/.gstack/projects/$SLUG/*-test-plan-*.md 2>/dev/null | head -1
    ```
 2. **Conversation context:** Check if a prior `/plan-eng-review` or `/plan-ceo-review` produced test plan output in this conversation
@@ -72,7 +72,7 @@ Write the report to both local and project-scoped locations:
 
 **Project-scoped:** Write test outcome artifact for cross-session context:
 ```bash
-SLUG=$(git remote get-url origin 2>/dev/null | sed 's|.*[:/]\([^/]*/[^/]*\)\.git$|\1|;s|.*[:/]\([^/]*/[^/]*\)$|\1|' | tr '/' '-')
+eval $(~/.claude/skills/gstack/bin/gstack-slug 2>/dev/null)
 mkdir -p ~/.gstack/projects/$SLUG
 ```
 Write to `~/.gstack/projects/{slug}/{user}-{branch}-test-outcome-{datetime}.md`