Fix timing footer being saved to context window

The timing footer (e.g., ⏱️ 19.4s | 💭 4.7s) was being saved to the
conversation history as a separate assistant message. This happened
because stream_completion_with_tools returns the timing footer in
TaskResult.response for display, but the caller was also saving it
to context.

Fix: Strip the timing footer (identified by \n\n⏱️) before saving
to context window. The timing footer remains display-only.

Also includes:
- Research tool blank line fix: only add visual separator for research
  tool output, not all tools
- Research tool webdriver propagation: pass parent's webdriver browser
  choice (Safari vs Chrome headless) to scout subprocess

crates/g3-cli/src/ui_writer_impl.rs

@@ -231,8 +231,6 @@ impl UiWriter for ConsoleUiWriter {
     }
 
     fn print_tool_timing(&self, duration_str: &str, tokens_delta: u32, context_percentage: f32) {
-        // Add blank line before footer for visual separation
-        println!();
         // Parse the duration string to determine color
         // Format is like "1.5s", "500ms", "2m 30.0s"
         let color_code = if duration_str.ends_with("ms") {
@@ -274,6 +272,12 @@ impl UiWriter for ConsoleUiWriter {
             ""
         };
 
+        // Add blank line before footer for research tool (its output is a full report)
+        if let Some(tool_name) = self.current_tool_name.lock().unwrap().as_ref() {
+            if tool_name == "research" {
+                println!();
+            }
+        }
         println!("└─ ⚡️ {}{}\x1b[0m  \x1b[2m{} ◉ | {:.0}%\x1b[0m", color_code, duration_str, tokens_delta, context_percentage);
         println!();
         // Clear the stored tool info