Address review feedback: restructure plugin for marketplace conventions

- Remove .mcp.json (not used in marketplace, add README instead)
- Add marketplace.json entry for plugin discovery
- Add README.md with MCP server setup guide, provider config, and troubleshooting
- Add tools: declaration to image-generator agent (functional fix)
- Move <example> blocks from YAML frontmatter to markdown body
- Remove unused tools: Read, Grep, Glob from prompt-crafter agent
- Remove redundant name: field from command frontmatter
- Use full MCP tool prefix (mcp__meigen__*) in commands
- Rewrite plugin.json description to factual style
- Pin npm version to meigen@1.2.5

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

plugins/meigen-ai-design/commands/find.md

@@ -1,7 +1,6 @@
 ---
-name: find
 description: >-
-  Quick gallery search. Use when user runs /meigen:find with keywords
+  Quick gallery search. Use when user runs /meigen-ai-design:find with keywords
   to browse inspiration.
 argument-hint: <keywords>
 ---
@@ -12,13 +11,13 @@ Search the curated gallery for inspiration. Show visual results immediately.
 
 ## Instructions
 
-1. Call `search_gallery` with query: `$ARGUMENTS`
+1. Call `mcp__meigen__search_gallery` with query: `$ARGUMENTS`
    - If no arguments provided, call with no query to get trending picks
    - Use limit: 6 for a good visual spread
 2. Display results as a compact list:
    - Number, preview image (markdown), one-line prompt excerpt, category
 3. End with: "Say a number to see the full prompt, or describe what you want to generate."
 
-If the user picks a number, call `get_inspiration` with that entry's ID to show the full prompt and images.
+If the user picks a number, call `mcp__meigen__get_inspiration` with that entry's ID to show the full prompt and images.
 
 Keep output visual and scannable. No long explanations.