docs: add comprehensive frontend landing page plan and download design skills

Add detailed landing page development plan in docs/frontend_landing_plan.md:
- Complete landing page structure (Hero, Problem/Solution, Features, Demo, CTA)
- Design guidelines from downloaded skills (typography, color, motion, composition)
- Security considerations (XSS prevention, input sanitization, CSP)
- Performance targets (LCP <2.5s, bundle <150KB, Lighthouse >90)
- Responsiveness and accessibility requirements (WCAG 2.1 AA)
- Success KPIs and monitoring setup
- 3-week development timeline with daily tasks
- Definition of Done checklist

Download 10+ frontend/UI/UX skills via universal-skills-manager:
- frontend-ui-ux: UI/UX design without mockups
- frontend-design-guidelines: Production-grade interface guidelines
- frontend-developer: React best practices (40+ rules)
- frontend-engineer: Next.js 14 App Router patterns
- ui-ux-master: Comprehensive design systems and accessibility
- ui-ux-systems-designer: Information architecture and interaction
- ui-ux-design-user-experience: Platform-specific guidelines
- Plus additional reference materials and validation scripts

Configure universal-skills MCP with SkillsMP API key for curated skill access.

Safety first: All skills validated before installation, no project code modified.

Refs: Universal Skills Manager (github:jacob-bd/universal-skills-manager)
Next: Begin Sprint 3 landing page development

.opencode/skills/frontend-developer/scripts/validate_compliance.py

@@ -0,0 +1,65 @@
+#!/usr/bin/env python3
+import sys
+import re
+import os
+
+def check_file(filepath):
+    """
+    Simple heuristic checks for frontend compliance.
+    """
+    with open(filepath, 'r') as f:
+        content = f.read()
+
+    errors = []
+    
+    # Check 1: Image Accessibility
+    # Matches <img ...> without alt=
+    img_tags = re.findall(r'<img[^>]*>', content)
+    for tag in img_tags:
+        if 'alt=' not in tag:
+            errors.append(f"ACCESSIBILITY: Found <img> tag without 'alt' attribute: {tag}")
+
+    # Check 2: Next.js Image Optimization
+    if 'next/image' in content or '<Image' in content:
+        # Check for sizes prop if not fill
+        if '<Image' in content and 'sizes=' not in content and 'fill' not in content:
+             errors.append("PERFORMANCE: Found <Image> component (Next.js) without 'sizes' attribute. Use 'sizes' for responsive hydration.")
+
+    # Check 3: React Anti-Pattern (Effect Fetching)
+    if 'useEffect' in content and 'fetch(' in content:
+        errors.append("ARCHITECTURE: Found 'fetch' inside 'useEffect'. Use Server Components, React Query, or SWR instead.")
+
+    # Check 4: Angular Legacy
+    if '*ngIf' in content:
+         errors.append("MODERNIZATION: Found '*ngIf'. Use modern Angular control flow '@if'.")
+
+    return errors
+
+def main():
+    if len(sys.argv) < 2:
+        print("Usage: python validate_compliance.py <file_or_directory>")
+        sys.exit(1)
+
+    target = sys.argv[1]
+    all_errors = []
+
+    if os.path.isfile(target):
+        all_errors.extend(check_file(target))
+    elif os.path.isdir(target):
+        for root, _, files in os.walk(target):
+            for file in files:
+                if file.endswith(('.tsx', '.jsx', '.vue', '.ts', '.js')):
+                    path = os.path.join(root, file)
+                    all_errors.extend(check_file(path))
+
+    if all_errors:
+        print("❌ Compliance Errors Found:")
+        for err in all_errors:
+            print(f"- {err}")
+        sys.exit(1)
+    else:
+        print("✅ No obvious compliance errors found (Heuristic Check).")
+        sys.exit(0)
+
+if __name__ == "__main__":
+    main()