docs: update README and schema for v2.0.0 changes

- Add OmO agent description as the default agent
- Update librarian model from anthropic/claude-sonnet-4-5 to opencode/big-pickle
- Add omo_agent configuration section with disable_build option
- Update both English and Korean README files
- Add omo_agent to JSON schema

🤖 GENERATED WITH ASSISTANCE OF [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)

assets/oh-my-opencode.schema.json

@@ -251,6 +251,17 @@
           "description": "Execute hooks from ~/.claude/settings.json, ./.claude/settings.json, ./.claude/settings.local.json"
         }
       }
+    },
+    "omo_agent": {
+      "type": "object",
+      "description": "Configuration for the default OmO agent behavior.",
+      "properties": {
+        "disable_build": {
+          "type": "boolean",
+          "description": "When true, hides the default Build agent. OmO becomes the only primary agent.",
+          "default": false
+        }
+      }
     }
   }
 }