Lupin 0.2.1: mix subagents with total control

The launch thread's most asked feature: per-subagent model and provider routing, with total control from Lupin.

• A global agents table in the config maps a route name to a model or a profile; the id claude-lupin-agent:<name> resolves through it.
• Put the id in an agent's frontmatter model:, the Agent tool model parameter, or CLAUDE_CODE_SUBAGENT_MODEL; declare the conventional subagents route and lupin run wires the env var for you.
• Edit the table from the CLI (lupin agents), the TUI (a opens agents mode) or POST /v1/lupin/agents (atomic). Hot reload everywhere, no restart.
• Every routed request is visible in the log and in lupin top / the sidecar as agent:<name>; an id naming a missing route serves on the normal path as agent:unknown:<name>, never an error.
• Opt-in end to end: no table, no behaviour change. Content routes never reroute an agent-routed request. Nothing new is published in the model picker.

Design record: ADR-47, SPEC-PROVIDERS §4decies. The wire facts that shaped it (no header or metadata identifies a subagent; the model id travels verbatim; CLAUDE_CODE_SUBAGENT_MODEL overrides frontmatter) were verified 2026-08-09 against the official docs and issue tracker.

Full changelog: https://github.com/Fanfulla/Lupin/blob/main/CHANGELOG.md