The spec document incorrectly defined permission fields (camera, microphone,
geolocation, clipboardWrite) as boolean types, but the SDK implementation
uses empty object types ({}).
This caused validation errors for MCP servers (like Hex) that followed
the spec and sent boolean values like `clipboardWrite: true`, when the
Zod schema expects `clipboardWrite: {}`.
The empty object design was intentional to allow future extensibility
(e.g., adding options like `{ required: true }`). This commit aligns
the spec documentation with the actual TypeScript types in spec.types.ts.
Fixes validation error:
`{ code: 'invalid_type', expected: 'object', received: 'boolean',
path: ['permissions', 'clipboardWrite'] }`