Addresses mara's review: each credential type gets its own PrivRequest
variant, making the exact priv surface visible in the wire protocol.
No runtime filename dispatch — the operation name is the gate.
- WriteAgentForgeToken { agent_name, token } → state/forge-token
- WriteAgentMatrixToken { agent_name, token } → state/matrix-token
- priv_client: two typed fns (write_agent_forge_token, write_agent_matrix_token)
- forge.rs: split mint_and_persist_token into mint_and_persist_agent_token
(priv) + mint_and_persist_core_token (direct write); drop dead token_path fn
- matrix.rs: call write_agent_matrix_token directly
7022cd3826