subagent model: opencode-go/deepseek-v4-flash

The operator enabled China-hosted models on the workspace, so deepseek-v4-flash
is available on the Go tier again (it was the model the weekly run used before
the host moved off ZEN, and it is the cheap/fast one for the per-recipe
subagents). Verified on the host: `opencode run --model
opencode-go/deepseek-v4-flash` answers.

The weekly run's MAIN agent moves to opencode-go/glm-5.3-flash separately, in
upgrader.env on the host.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FqkQq3CDmFWcQ7u1LzoyRz

opencode.json

@@ -2,7 +2,7 @@
   "$schema": "https://opencode.ai/config.json",
   "agent": {
     "general": {
-      "model": "opencode-go/glm-5.2"
+      "model": "opencode-go/deepseek-v4-flash"
     }
   }
 }