feat: add MCP profiles library with builtin templates

Pre-configured profile templates for filesystem, GitHub, PostgreSQL,
Slack, memory, and fetch MCP servers. Includes registry, validation,
instantiation utilities, and .mcp.json generation.

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

src/shared/src/profiles/templates/index.ts

@@ -0,0 +1,6 @@
+export { filesystemTemplate } from './filesystem.js';
+export { githubTemplate } from './github.js';
+export { postgresTemplate } from './postgres.js';
+export { slackTemplate } from './slack.js';
+export { memoryTemplate } from './memory.js';
+export { fetchTemplate } from './fetch.js';