design-systems: add 74 brand DESIGN.md files (VoltAgent/awesome-design-md)

- 74 brands: airbnb, stripe, apple, figma, linear, vercel, etc.
- 147 files: DESIGN.md + README.md per brand (~2.1 MB)
- Each DESIGN.md contains structured brand analysis (colors, typography, components)
- Updated 00-overview.md with new design-systems directory

concepts/design-systems.md

@@ -0,0 +1,49 @@
+---
+title: Brand Identity Design
+description: Building consistent brand identity across web presence.
+tags: [brand, identity, logo, colors, typography, consistency]
+---
+
+# Brand Identity Design
+
+## Brand Elements Hierarchy
+
+### 1. Logo
+- Primary: Full logo with wordmark
+- Secondary: Icon-only for favicons
+- Monochrome: For dark/light backgrounds
+- Minimum size: 32px height
+
+### 2. Color Palette
+```
+Brand Colors:
+├── Primary: #6366f1
+├── Secondary: #8b5cf6
+├── Accent: #10b981
+└── Neutrals: #f5f5f5, #a0a0a0, #666666, #111111
+```
+
+### 3. Typography
+- Display font: For headings
+- Body font: For content
+- Max 2 type families per brand
+
+### 4. Imagery Style
+- Photography: Consistent lighting, mood
+- Illustrations: Flat, isometric, or abstract
+- Icons: 2px stroke, consistent style
+
+## Brand Voice Guidelines
+
+| Channel | Tone | Example |
+|---------|------|---------|
+| Website | Professional, clear | "Simplify your workflow" |
+| Social | Conversational | "Try it out today!" |
+| Email | Personal, direct | "Hi John, we noticed..." |
+| Support | Empathetic, helpful | "Let's figure this out together" |
+
+## Anti-Patterns
+- Never use more than 2 primary colors
+- Never change fonts without approval
+- Never stretch or distort logo
+- Never ignore brand guidelines