fix(agents): Use exclude pattern for tools config to enable MCP tools

Changed agent tools configuration from include pattern (listing allowed tools)
to exclude pattern (listing disabled tools only). This ensures MCP tools like
websearch_exa, context7, and grep_app are available to agents by default.

Affected agents: librarian, oracle, explore, multimodal-looker

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

src/agents/oracle.ts

@@ -8,7 +8,7 @@ export const oracleAgent: AgentConfig = {
   temperature: 0.1,
   reasoningEffort: "medium",
   textVerbosity: "high",
-  tools: { write: false, edit: false, read: true, task: false, call_omo_agent: true, background_task: false },
+  tools: { write: false, edit: false, task: false, background_task: false },
   prompt: `You are a strategic technical advisor with deep reasoning capabilities, operating as a specialized consultant within an AI-assisted development environment.
 
 ## Context