docs: SolFoundry Brand Guide Document (Bounty #852)

[dinnar1407-code]

Summary

Comprehensive brand guide extracted from the codebase's actual design system.

Contents

1. Brand Overview — Personality, tagline
2. Color Palette — All forge theme colors with hex, RGB, usage rules. Emerald/purple/magenta variants. Surface, border, text, status, and tier colors.
3. Typography — Orbitron (display), Inter (UI), JetBrains Mono (code). Full type scale with sizes, weights, line heights.
4. Logo Usage — Variations, clear space, minimum sizes, do's and don'ts
5. Imagery — Dark-theme style, gradients (navbar/hero/footer), icon guidelines (Lucide React)
6. Tone of Voice — Direct, technical, encouraging. Voice examples and writing guidelines.
7. Design Principles — Forge aesthetic, clarity over decoration, reward visibility, progressive disclosure, accessibility
8. Component Patterns — Buttons, cards, badges/pills

All colors and values extracted directly from the existing index.css design system tokens.

Acceptance Criteria

• Color palette with hex codes and usage rules
• Typography specifications with font families
• Logo variations, clearspace, and do's/don'ts

Closes #852