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."

bin/gstack-slug

@@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+# gstack-slug — output project slug and sanitized branch name
+# Usage: eval $(gstack-slug)  → sets SLUG and BRANCH variables
+# Or:    gstack-slug           → prints SLUG=... and BRANCH=... lines
+set -euo pipefail
+SLUG=$(git remote get-url origin 2>/dev/null | sed 's|.*[:/]\([^/]*/[^/]*\)\.git$|\1|;s|.*[:/]\([^/]*/[^/]*\)$|\1|' | tr '/' '-')
+BRANCH=$(git rev-parse --abbrev-ref HEAD 2>/dev/null | tr '/' '-')
+echo "SLUG=$SLUG"
+echo "BRANCH=$BRANCH"