fix: skill installer writes the scoped package spec into MCP configs

[brainsparker]

Why

Found during the final end-to-end verification of 0.2.1. The skill installer works, but the MCP entry it writes into Claude/Cursor configs still says npx -y -p you-md you-md-mcp. The unscoped you-md package does not exist on npm (name blocked as too similar to the unrelated youmd package), so the installed skill 404s the moment the AI tool actually tries to launch the MCP server. #30 fixed the README's manual config but missed this hardcoded entry.

What changed

• src/cli/commands/skill.ts: MCP_ENTRY now points npx at @brainsparker/you-md. The "you-md" key inside mcpServers and the you-md-mcp bin name are unchanged, so existing installs upgrade in place on the next skill install run.
• test/cli/skill.test.ts: regression test asserting the entry references the scoped package and never the unscoped name.

Validation

• Build clean, lint clean, 173/173 tests pass
• Functional check: ran skill install against a simulated Claude Code config; the written entry is ["-y", "-p", "@brainsparker/you-md", "you-md-mcp"]

After merging

Publish 0.2.2 (npm version patch && npm publish). Users who installed the skill from 0.2.0 or 0.2.1 should re-run you-md skill install once to rewrite the entry.