Fix server: remove DEFAULT_OPENCODE_LOCAL_MODEL from agents route

Same issue as the UI fix — merge conflict resolution kept HEAD's
reference to the removed constant. OpenCode uses strict model
selection with no default.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/routes/agents.ts

@@ -37,7 +37,6 @@ import {
   DEFAULT_CODEX_LOCAL_MODEL,
 } from "@paperclipai/adapter-codex-local";
 import { DEFAULT_CURSOR_LOCAL_MODEL } from "@paperclipai/adapter-cursor-local";
-import { DEFAULT_OPENCODE_LOCAL_MODEL } from "@paperclipai/adapter-opencode-local";
 import { ensureOpenCodeModelConfiguredAndAvailable } from "@paperclipai/adapter-opencode-local/server";
 
 export function agentRoutes(db: Db) {
@@ -196,9 +195,7 @@ export function agentRoutes(db: Db) {
       }
       return next;
     }
-    if (adapterType === "opencode_local" && !asNonEmptyString(next.model)) {
-      next.model = DEFAULT_OPENCODE_LOCAL_MODEL;
-    }
+    // OpenCode requires explicit model selection — no default
     if (adapterType === "cursor" && !asNonEmptyString(next.model)) {
       next.model = DEFAULT_CURSOR_LOCAL_MODEL;
     }