Allow stand-alone agents to work without mandatory teams

[nocodeafrica]

Directly mentioning an agent can currently fail because Colony requires a coordination team, even when the intended assignee is clear. This change lets the named agent own the task without team membership or a mandatory reviewer.

Direct assignments retain the mentioned agent across chat planning, relay validation, CLI messages, runtime execution and ledger attribution. Hiring and startup no longer automatically enrol agents into coordination teams. Desktop and mobile accept optional team references, while explicitly selected team workflows retain their membership, ownership and review checks. Legacy agent identities are repaired before assignment without replacing their existing metadata.

Validation includes regressions for direct assignment without a published team, replay idempotency, completion without a reviewer, invalid persona rejection, optional work tags and preserved team workflows. Focused first-job tests passed 238 cases; execution-fixture tests passed 37 cases. New desktop receipt and provider-command regressions were observed failing before their fixes. Hosted checks are running on the latest commit, including Rust CLI tests and packaged first-job execution.

The packaged test uses a real relay, native agent processes and CLI commands with synthetic model responses and fixture funds. It now checks that direct work starts and completes with no team records. That latest packaged result is still pending, so this PR remains draft. Installed-app messaging with a live provider remains unproven. Relay, runtime and client readers must roll out together.