Extract the agent registry to a shared agents.json and have both
route.sh (agent → model) and install-opencode.sh (ollama-cloud provider
models map) derive from it, so the two lists can no longer drift.
route.sh now copies agents.json to /tmp/agents.json instead of an inline
heredoc. install-opencode.sh builds the ollama-cloud map by
collecting every registry model with the prefix and
stripping it — non-ollama-cloud models (e.g. @lead's anthropic/claude-opus,
the local ornith:35b) are excluded by construction.
Resolves#31.
