Get a normalized, provider-agnostic trust signal for a wallet address or agent identifier. Returns a 0-1 score with a confidence weight, or band='unknown' when no source has an opinion. ADVISORY ONLY — an optional input to agent decisions alongside technical and sentiment signals. Never a compliance, sanctions or settlement control. 'unknown' means no data, NOT untrustworthy. It is NOT your MCP tool-access tier (unknown/recognized/trusted/allied): that is _meta.trust_level on every MCP answer and GET /mcp/v1/agents/me. When the subject names a platform identity (agent id, agent name, username), the answer also carries ladder — the tier that identity holds, read from the same field the tool gate reads.