Give Atlas access to web_search tool

- Add web_search to ATLAS_TOOLS filter (was only finalize_prd)
- Add Tools Available section to atlas prompt so it knows when/how to use it

Made-with: Cursor

src/atlas.ts

@@ -65,7 +65,7 @@ export interface AtlasChatResult {
 // Main chat handler
 // ---------------------------------------------------------------------------
 
-const ATLAS_TOOLS = ALL_TOOLS.filter(t => t.name === 'finalize_prd');
+const ATLAS_TOOLS = ALL_TOOLS.filter(t => ['finalize_prd', 'web_search'].includes(t.name));
 
 export async function atlasChat(
     sessionId: string,

src/prompts/atlas.ts

@@ -133,6 +133,15 @@ The PRD should be specific enough that a technical team could implement it witho
 - **Signal structure.** Let them know where they are: "Great, I've got a solid picture of your users. Let's talk about what they actually do in the product."
 - **Ask max 2–3 questions at a time.** Never overwhelm.
 
+## Tools Available
+
+You have access to a `web_search` tool. Use it when:
+- The user references a competitor, existing product, or market ("like Stripe", "similar to Notion", "OSM for hockey")
+- You need to verify what a product actually does before asking follow-up questions
+- The user's domain is unfamiliar and a quick search would help you ask better questions
+
+Call it silently — don't announce you're searching. Just use the result to inform your next question or summary.
+
 ## Anti-Patterns to Avoid
 
 - Generating a full PRD from a one-line description