Refactor project name from "Open Claude Design" to "Open Design" (#1)

* Refactor project name from "Open Claude Design" to "Open Design"

- Updated project name in package.json, package-lock.json, and README files.
- Changed CLI commands and references from "ocd" to "od".
- Adjusted file structure references in documentation and code to reflect new naming conventions.
- Enhanced .gitignore to include new runtime data files.
- Updated metadata in LICENSE file to match new project name.

* Add contributing guidelines in English and Chinese

- Introduced CONTRIBUTING.md and CONTRIBUTING.zh-CN.md to provide clear instructions for contributors.
- Outlined contribution types, local setup instructions, and merging criteria for skills and design systems.
- Enhanced README files to reference the new contributing guidelines.

skills/web-prototype/SKILL.md

@@ -12,7 +12,7 @@ triggers:
   - "single page"
   - "marketing page"
   - "homepage"
-ocd:
+od:
   mode: prototype
   platform: desktop
   scenario: design
@@ -83,7 +83,7 @@ Wrap `index.html` in `<artifact>` tags. One sentence before describing what's th
 - **Display font is serif** (Iowan Old Style / Charter / Georgia in the seed). Sans for body. Mono for numerics, captions, eyebrows.
 - **Image placeholders, not external URLs.** Use the `.ph-img` class — never link to a stock photo CDN.
 - **Mobile reflow already works** via the seed's media query at 920px. Don't break it by adding fixed widths.
-- **`data-ocd-id` on every `<section>`** so comment mode can target it.
+- **`data-od-id` on every `<section>`** so comment mode can target it.
 
 ## Output contract