Expose MCP tool safeguards inline

[kopachlager]

What changed

• declares all four MCP tool annotations directly on every tool
• declares each Zod input schema directly on its tool definition
• places a visible structured error boundary in every handler
• adds validation coverage for every schema and handler
• prepares version 0.1.6 and refreshes the MCP SDK dependency

Why

The runtime already exposed these safeguards, but registry static analyzers could not follow the shared constants, schemas, and wrapper. This refactor preserves behavior while making the declarations directly auditable.

Verification

• npm audit: 0 vulnerabilities
• npm test: 19 passing
• npm run test:coverage: 99.68% lines
• npm run check
• npm run pack:check