refactor: Add new V2.0 logo with dark/light mode support to all markdown files

- Update all main markdown files (INDEX.md, LEARNING-ROADMAP.md, QUICK_REFERENCE.md, CONTRIBUTING.md, claude_concepts_guide.md, resources.md) with new responsive picture element
- Add logo to all subdirectory README files in feature folders (01-10) and plugins
- Replace old markdown image syntax with HTML picture element for dark/light mode adaptation
- Logo automatically displays dark mode version when system prefers dark mode
- Maintain correct relative paths for all nesting levels (../, ../../, etc.)
- Update README.md with new logo syntax

All markdown files now use the new V2.0 starburst logo design with professional dark/light mode support.

CLAUDE.md

@@ -1,18 +0,0 @@
-<!-- OPENSPEC:START -->
-# OpenSpec Instructions
-
-These instructions are for AI assistants working in this project.
-
-Always open `@/openspec/AGENTS.md` when the request:
-- Mentions planning or proposals (words like proposal, spec, change, plan)
-- Introduces new capabilities, breaking changes, architecture shifts, or big performance/security work
-- Sounds ambiguous and you need the authoritative spec before coding
-
-Use `@/openspec/AGENTS.md` to learn:
-- How to create and apply change proposals
-- Spec format and conventions
-- Project structure and guidelines
-
-Keep this managed block so 'openspec update' can refresh the instructions.
-
-<!-- OPENSPEC:END -->