fix: rename linear mcp id to linear-mcp to resolve duplicate id

[saoudrizwan]

Problem

main currently fails validation:

registry/mcps/linear/entry.json: duplicate id "linear"

Two PRs landed independently and collided:

• feat: add cline/plugins entries and feature them #6 added the cline/plugins catalog, including a linear plugin (registry/plugins/linear/) — the @linear/sdk scripting skill.
• feat: add MCP catalog entries #4 added the MCP catalog, including a linear MCP (registry/mcps/linear/) — the official remote Linear MCP server.

Marketplace ids are globally unique across types (seenIds is a single set in scripts/generate.mjs), so having both a plugin and an mcp with id linear breaks the build on main.

Fix

Rename the MCP entry's id and directory from linear to linear-mcp, leaving the plugin to keep the plain linear id.

• The MCP install.args are unchanged (cline mcp install linear --transport http https://mcp.linear.app/mcp) — the server name the user types is independent of the marketplace id.
• Display name stays "Linear"; homepage unchanged.

Testing

npm run validate passes (166 entries).