feat(capacity-adapter): default vision fallback to mimo-v2.6-flash-free

Register mimo-v2.6-flash-free on opencode-zen (chat lane) with a v2.6
capability pattern, and switch the vision adapter default from the old
mimo-v2.5-free.

Co-Authored-By: Claude Code <noreply@anthropic.com>

open-sse/providers/registry/opencode-zen.js

@@ -106,6 +106,7 @@ export default {
     { id: "union-alpha", name: "Union Alpha", supportedFormats: ["claude"] },
     // Free tier on the keyed lane (chat completions)
     { id: "deepseek-v4-flash-free", name: "DeepSeek V4 Flash Free", supportedFormats: ["openai"] },
+    { id: "mimo-v2.6-flash-free", name: "MiMo V2.6 Flash Free", supportedFormats: ["openai"] },
     { id: "mimo-v2.5-free", name: "MiMo V2.5 Free", supportedFormats: ["openai"] },
     { id: "ling-3.0-flash-fin-free", name: "Ling 3.0 Flash Fin Free", supportedFormats: ["openai"] },
     { id: "nemotron-3-ultra-free", name: "Nemotron 3 Ultra Free", supportedFormats: ["openai"] },
@@ -113,7 +114,18 @@ export default {
     // Free tier on the keyed lane (responses)
     { id: "muse-spark-1.3-contributor-free", name: "Muse Spark 1.3 Contributor Free", targetFormat: "openai-responses", supportedFormats: ["openai-responses"] },
     { id: "muse-spark-1.2-contributor-free", name: "Muse Spark 1.2 Contributor Free", targetFormat: "openai-responses", supportedFormats: ["openai-responses"] },
+    // System One (Jev) decision models on the native /systemone endpoint
+    { id: "jev-1.13", name: "Jev 1.13", kind: "decision" },
+    { id: "jev-1.13-free", name: "Jev 1.13 Free", kind: "decision" },
   ],
+  serviceKinds: ["llm", "systemone"],
+  systemoneConfig: {
+    baseUrl: "https://opencode.ai/zen/v1/systemone",
+    headers: {
+      "x-opencode-client": "desktop",
+      "User-Agent": "opencode/1.18.31",
+    },
+  },
   modelsFetcher: { url: "https://opencode.ai/zen/v1/models", type: "opencode-free" },
   passthroughModels: true,
   features: {