Widens the salvaged #91323 fix (@vinsew): the effort vocabulary moves to
agent.reasoning_effort (OX_ALPHA_EFFORTS/OVERRIDES, the declared-policy
home every other model vocabulary lives in), and the translation is
shared between the opencode-zen profile and the keyless opencode-free
profile — Ox Alpha is reachable through both, and the free profile
previously dropped effort entirely.
Live-verified: medium clamps to low (raw medium 400s: 'This model always
engages in thinking... use low, high, or max'), xhigh rounds to max, and
full agent turns with effort=medium complete on BOTH providers.