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/ui-ux-master/references/apple-watchos.md

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+# watchOS Design Patterns
+
+Glanceable, quick interactions for Apple Watch.
+
+## Core Principles
+- **Glanceable:** Information at a glance
+- **Actionable:** Complete tasks quickly
+- **Responsive:** Interactions feel immediate
+
+## Layout
+- **SF Compact Rounded:** watchOS system font
+- Edge-to-edge content
+- Vertical scrolling preferred
+- Digital Crown for scrolling/zooming
+
+## Components
+- **Lists:** Primary navigation pattern
+- **Buttons:** Large, easy to tap
+- **Digital Crown:** Scroll, zoom, discrete values
+- **Side Button:** Access Dock, Apple Pay
+
+## Always-On Display
+- Simplified UI when wrist down
+- Essential info visible
+- Reduced brightness
+- Updates every second
+
+## Complications
+- **Circular, Rectangular, Text-only** styles
+- Update intelligently (timeline)
+- Tappable to launch app
+- Support all watch faces
+
+## Notifications
+- **Short Look:** App icon + title
+- **Long Look:** Full notification (raise wrist)
+- Actionable buttons
+- Quick replies
+
+---
+
+*Full watchOS patterns available at official Apple HIG*