feat: Add 57 skills from vibeship-spawner-skills

Ported 3 categories from Spawner Skills (Apache 2.0):
- AI Agents (21 skills): langfuse, langgraph, crewai, rag-engineer, etc.
- Integrations (25 skills): stripe, firebase, vercel, supabase, etc.
- Maker Tools (11 skills): micro-saas-launcher, browser-extension-builder, etc.

All skills converted from 4-file YAML to SKILL.md format.
Source: https://github.com/vibeforge1111/vibeship-spawner-skills

skills/clerk-auth/SKILL.md

@@ -0,0 +1,56 @@
+---
+name: clerk-auth
+description: "Expert patterns for Clerk auth implementation, middleware, organizations, webhooks, and user sync Use when: adding authentication, clerk auth, user authentication, sign in, sign up."
+source: vibeship-spawner-skills (Apache 2.0)
+---
+
+# Clerk Authentication
+
+## Patterns
+
+### Next.js App Router Setup
+
+Complete Clerk setup for Next.js 14/15 App Router.
+
+Includes ClerkProvider, environment variables, and basic
+sign-in/sign-up components.
+
+Key components:
+- ClerkProvider: Wraps app for auth context
+- <SignIn />, <SignUp />: Pre-built auth forms
+- <UserButton />: User menu with session management
+
+
+### Middleware Route Protection
+
+Protect routes using clerkMiddleware and createRouteMatcher.
+
+Best practices:
+- Single middleware.ts file at project root
+- Use createRouteMatcher for route groups
+- auth.protect() for explicit protection
+- Centralize all auth logic in middleware
+
+
+### Server Component Authentication
+
+Access auth state in Server Components using auth() and currentUser().
+
+Key functions:
+- auth(): Returns userId, sessionId, orgId, claims
+- currentUser(): Returns full User object
+- Both require clerkMiddleware to be configured
+
+
+## ⚠️ Sharp Edges
+
+| Issue | Severity | Solution |
+|-------|----------|----------|
+| Issue | critical | See docs |
+| Issue | high | See docs |
+| Issue | high | See docs |
+| Issue | high | See docs |
+| Issue | medium | See docs |
+| Issue | medium | See docs |
+| Issue | medium | See docs |
+| Issue | medium | See docs |