feat: add aso-audit skill for App Store and Google Play optimization

Live ASO audit skill that fetches real store listings, scores across 6
weighted dimensions (Title, Description, Visuals, Ratings, Metadata,
Conversion), and produces a prioritized action plan.

Features brand maturity system (Dominant/Established/Challenger) that
adjusts scoring to avoid penalizing deliberate brand choices by
household-name apps.

Backed by official Apple/Google developer docs and industry benchmarks
from AppTweak, SplitMetrics, and Sensor Tower.

.claude-plugin/marketplace.json

@@ -12,13 +12,14 @@
   "plugins": [
     {
       "name": "marketing-skills",
-      "description": "33 marketing skills for technical marketers and founders: CRO, copywriting, cold email, SEO, AI SEO, paid ads, ad creative, churn prevention, pricing strategy, referral programs, revenue operations, sales enablement, customer research, site architecture, and more",
+      "description": "34 marketing skills for technical marketers and founders: ASO, CRO, copywriting, cold email, SEO, AI SEO, paid ads, ad creative, churn prevention, pricing strategy, referral programs, revenue operations, sales enablement, customer research, site architecture, and more",
       "source": "./",
       "strict": false,
       "skills": [
         "./skills/ab-test-setup",
         "./skills/ad-creative",
         "./skills/ai-seo",
+        "./skills/aso-audit",
         "./skills/analytics-tracking",
         "./skills/churn-prevention",
         "./skills/cold-email",