OpenCode: refresh Zen catalog and send --variant #742

Parent: #738
Needs: per-model effort lists (child of #738) for --variant

User-visible bug

OpenCode's Zen catalog in electron/providers.js is a stale opencode models snapshot (comment cites v1.17.12, which is also the live CLI here, but the ids have already moved).

Gone from live, still in Solenta (and tests):

• opencode/ling-3.0-tiny-free
• opencode/longcat-2.0-free
• opencode/north-mini-code-free (currently recommended, pinned by electron/test/providers.test.js)

On live, missing from Solenta:

• opencode/hy3-free (variants: low, medium, high)
• opencode/nemotron-3.5-lightning-free

Effort: opencode run --help documents --variant as provider-specific reasoning effort. Verbose catalog lists per-model variants (deepseek-v4-flash-free: low/medium/high/max; hy3-free: low/medium/high; big-pickle: none). Solenta sets efforts: [] and the emit path is a never-taken stub (--variant should-not-appear). The effort pill is hidden.

What to ship

1. Replace the OpenCode models / modelInfo arrays from a fresh opencode models --verbose. Pick a new recommended (north-mini-code-free is gone). Copy labels, descriptions, vendors, and limit.context into contextTokens only when the verbose payload states it.
2. Per-model efforts from that model's variants keys. Intersection with Solenta's ReasoningEffort union. Skip models with empty variants (pill stays hidden).
3. buildArgs: maybeEmitEffort on the selected model's variants, emit --variant <level> before the trailing prompt.
4. Update electron/test/providers.test.js (it currently requires opencode/north-mini-code-free).

Verify

• opencode run --format json -m opencode/hy3-free --variant high "ping" argv shape: prompt last, variant not swallowing the prompt.
• A model with empty variants must not receive --variant.

Files

electron/providers.js (OpenCode entry), electron/test/providers.test.js, electron/test/reasoning-effort.test.js.