fix(deps): pre-install @modelcontextprotocol/server-filesystem locally

User report: \`enchanter\` boots the cockpit cleanly but RECENT EVENTS
stays empty for 30-60 seconds while the tab title shows
\`npm exec @modelcontextpro...\`. Cause: live.ts spawns
\`npx -y @modelcontextprotocol/server-filesystem\` and on a fresh
clone npm has to fetch the package from the registry first. The
inspector itself is fine — there are no events to render because
live.ts hasn't gotten past the spawn yet.

Add the MCP filesystem server to devDependencies so npm install
puts it in node_modules/. \`npx -y\` then resolves locally and the
producer starts emitting events within a second or two of \`enchanter\`
launch instead of waiting on a network fetch.

Author: klaiderman