Remove tool.running event handling, keep tool tracking only

The tool tracking approach (tracking ToolCall/ToolResult events to extend
timeout) works without any OpenCode changes. Removed the speculative
tool.running/tool.progress event handling that would require OpenCode
modifications.

src/opencode/mod.rs

@@ -1256,41 +1256,9 @@ fn parse_sse_event(
     }
 
     // Treat most events as meaningful activity EXCEPT server heartbeats.
-    // tool.running events indicate a long-running tool is still executing - these
-    // ARE meaningful activity and should reset the inactivity timeout.
     let activity = event_type != "server.heartbeat";
 
     let event = match event_type {
-        // Tool progress events - sent by OpenCode while a tool is still running.
-        // These reset the inactivity timeout to prevent premature disconnection.
-        "tool.running" | "tool.progress" => {
-            let tool_call_id = props
-                .get("callID")
-                .or_else(|| props.get("tool_call_id"))
-                .and_then(|v| v.as_str())
-                .unwrap_or("unknown");
-            let tool_name = props
-                .get("tool")
-                .or_else(|| props.get("name"))
-                .and_then(|v| v.as_str())
-                .unwrap_or("unknown");
-            let elapsed = props
-                .get("elapsed_seconds")
-                .or_else(|| props.get("elapsed"))
-                .and_then(|v| v.as_u64())
-                .unwrap_or(0);
-
-            tracing::debug!(
-                tool_call_id = %tool_call_id,
-                tool_name = %tool_name,
-                elapsed_seconds = elapsed,
-                "Tool still running - heartbeat received"
-            );
-
-            // Don't emit an event to the UI, just acknowledge the activity
-            // (activity = true above already resets the timeout)
-            None
-        }
         // OpenAI Responses-style streaming
         "response.output_text.delta" => {
             let delta = props