feat: new MCP tools and resources

[marthendalnunes]

Description

This PR adds MCP tools and resource templates for username proofs and verifications.

Added tools

• get_username_proof
• get_username_proofs_by_fid
• get_verification
• get_all_verification_messages_by_fid

Added resources

• waypoint://username-proofs/by-name/{name}
• waypoint://username-proofs/{fid}
• waypoint://verifications/{fid}/{address}
• waypoint://verifications/all-by-fid/{fid}

Implementation updates

• Added request schemas and hooked new endpoints through MCP handlers, DataContext, and hub provider.
• Extended resource URI parsing/routing for the new resource templates.
• Improved verification response handling (add/remove variants, invalid address input, not-found responses).

Docs

• Updated docs/mcp.md with new tools/resources, examples, and clarified wording for resource scope and username proof types.

Misc

• Cargo.lock includes a waypoint version bump (2026.2.3 -> 2026.2.4).

Type of change

• New feature (non-breaking change that adds functionality)