Submit Cline MCP/plugin listing

Parent: #45

## Goal
Decide and submit the Build with WordPress Cline integration through the official Cline distribution surface.

## Evidence
- MCP docs: https://docs.cline.bot/mcp/mcp-overview
- MCP Marketplace docs: https://docs.cline.bot/mcp/mcp-marketplace.md
- Plugin docs: https://docs.cline.bot/customization/plugins.md
- Cline documents MCP Marketplace install and manual MCP config paths.
- Generated output: `plugins/cline/`.

## Tasks
- Decide whether to submit a WordPress Studio MCP Marketplace entry, a Cline plugin, or both.
- Validate `plugins/cline/` against current Cline rules/skills/MCP/plugin guidance.
- Prepare the required submission artifact or upstream listing request.
- Record the submission URL/status back in #45.