Execute Plan: Stream more patches to the FE (vibe-kanban) (#298)

* ## Summary

I've successfully implemented the fast catch-up streaming optimization in [`backend/src/routes/stream.rs`](file:///private/var/folders/kr/jdxkcn7129j376nrg0stj9zm0000gn/T/vibe-kanban/vk-03fe-execute-pl/backend/src/routes/stream.rs#L72-L110). 

**Key changes:**
- **Added pre-loop catch-up phase** before line 72 that immediately processes all historical entries when `since_batch_id` is provided
- **Fast batch sending** without polling delays for non-Gemini executors 
- **Proper cursor management** to seamlessly transition to normal polling after catch-up
- **Performance improvement**: Eliminates 400+ polling iterations for catch-up scenarios

The implementation handles edge cases properly and maintains compatibility with existing Gemini streaming while dramatically speeding up resumable streaming for other executors.

* Cleanup script

backend/src/routes/stream.rs

@@ -69,6 +69,48 @@ pub async fn normalized_logs_stream(
         let since = query.since_batch_id.unwrap_or(1);
         let mut fallback_batch_id: u64 = since + 1;
 
+        // Fast catch-up phase for resumable streaming
+        if let Some(since_batch) = query.since_batch_id {
+            if !is_gemini {
+                // Load current process state to get all available entries
+                if let Ok(Some(proc)) = ExecutionProcess::find_by_id(&app_state.db_pool, process_id).await {
+                    if let Some(stdout) = &proc.stdout {
+                        // Create executor and normalize logs to get all entries
+                        if let Some(executor) = proc.executor_type
+                            .as_deref()
+                            .unwrap_or("unknown")
+                            .parse::<crate::executor::ExecutorConfig>()
+                            .ok()
+                            .map(|cfg| cfg.create_executor())
+                        {
+                            if let Ok(normalized) = executor.normalize_logs(stdout, &proc.working_directory) {
+                            // Send all entries after since_batch_id immediately
+                            let start_entry = since_batch as usize;
+                            let catch_up_entries = normalized.entries.get(start_entry..).unwrap_or(&[]);
+
+                            for (i, entry) in catch_up_entries.iter().enumerate() {
+                                let batch_data = BatchData {
+                                    batch_id: since_batch + 1 + i as u64,
+                                    patches: vec![serde_json::json!({
+                                        "op": "add",
+                                        "path": "/entries/-",
+                                        "value": entry
+                                    })],
+                                };
+                                yield Ok(Event::default().event("patch").data(serde_json::to_string(&batch_data).unwrap_or_default()));
+                            }
+
+                                // Update cursors to current state
+                                last_entry_count = normalized.entries.len();
+                                fallback_batch_id = since_batch + 1 + catch_up_entries.len() as u64;
+                                last_len = stdout.len();
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
         loop {
             interval.tick().await;
 
@@ -156,10 +198,10 @@ pub async fn normalized_logs_stream(
                 }
 
                 // 5. Compute patches for any new entries
-                let new_entries = [&normalized.entries[last_entry_count - 1]];
-                if new_entries.is_empty() {
+                if last_entry_count >= normalized.entries.len() {
                     continue;
                 }
+                let new_entries = [&normalized.entries[last_entry_count]];
                 let patches: Vec<Value> = new_entries
                     .iter()
                     .map(|entry| serde_json::json!({