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/multimodal-looker.ts

@@ -6,7 +6,7 @@ export const multimodalLookerAgent: AgentConfig = {
   mode: "subagent",
   model: "google/gemini-2.5-flash",
   temperature: 0.1,
-  tools: { Read: true, background_task: false },
+  tools: { write: false, edit: false, bash: false, background_task: false },
   prompt: `You interpret media files that cannot be read as plain text.
 
 Your job: examine the attached file and extract ONLY what was requested.