Move WebDriver instructions from main prompt to scout agent

Simplified the main system prompt's web research section to just direct
users to the research tool. Moved the detailed WebDriver usage instructions
to scout.md where they belong, since the scout agent is the one that
actually uses WebDriver for research.

Main prompt now simply says: use the research tool for web research.
Scout agent now has the full WebDriver best practices documentation.

agents/scout.md

@@ -93,3 +93,23 @@ You succeed if:
 - No context bloat is introduced.
 
 If nothing meets the bar, saying so is OK.
+
+---
+
+## WebDriver Usage
+
+You have access to WebDriver browser automation tools for web research.
+
+**How to use WebDriver:**
+1. Call `webdriver_start` to begin a browser session
+2. Use `webdriver_navigate` to go to URLs (search engines, documentation sites, etc.)
+3. **IMPORTANT**: Always use `webdriver_get_page_source` with `save_to_file` parameter to save the page HTML to disk
+4. Read the saved HTML file with `read_file` to extract the information you need
+5. Call `webdriver_quit` when done
+
+**Best practices:**
+- Do NOT use `webdriver_screenshot` or try to decode page content visually - always save HTML to disk and read it
+- Save pages to the `tmp/` subdirectory (e.g., `tmp/search_results.html`)
+- Parse the HTML text content to find what you need
+- For search engines, look for result links and titles in the HTML
+- Close the WebDriver session when you're done to free resources