remove arrow support for natsbridge_csr.js

docs/spec.md

@@ -176,6 +176,7 @@ await smartsend("/agent/v1/process", data)
 | All | `String` | `"text"` |
 | All | `Dict`/`Object` | `"dictionary"` |
 | Desktop | `DataFrame` | `"arrowtable"` or `"jsontable"` |
+| Browser | `Array` of objects | `"jsontable"` (only table type) |
 | All | `Array` of objects | `"jsontable"` |
 | All | `Uint8Array`/`Buffer`/`bytes` | `"binary"` |
 | Desktop | `Arrow.Table` | `"arrowtable"` |
@@ -203,8 +204,8 @@ await smartsend("/agent/v1/process", data)
 |-------|-------------|---------------------|------------------|
 | `text` | Plain text string | All | `base64` |
 | `dictionary` | JSON object/dictionary | All | `base64`, `json` |
-| `arrowtable` | Apache Arrow IPC table | Desktop (Julia/JS/Python) | `base64`, `arrow-ipc` |
-| `jsontable` | JSON array of objects | All | `base64`, `json` |
+| `arrowtable` | Apache Arrow IPC table | Desktop (Julia/Python/Node.js) | `base64`, `arrow-ipc` |
+| `jsontable` | JSON array of objects | All (including Browser) | `base64`, `json` |
 | `image` | Binary image data | All | `base64` |
 | `audio` | Binary audio data | All | `base64` |
 | `video` | Binary video data | All | `base64` |
@@ -613,7 +614,7 @@ function fileserver_download_handler(
 
 ## Platform-Specific Constraints
 
-### Desktop (Julia/JS/Python)
+### Desktop (Julia/Python/Node.js)
 
 | Feature | Status | Notes |
 |---------|--------|-------|
@@ -623,6 +624,16 @@ function fileserver_download_handler(
 | File server download | ✅ Supported | HTTP/HTTPS |
 | Size threshold | 500KB | Configurable |
 
+### Browser (JavaScript)
+
+| Feature | Status | Notes |
+|---------|--------|-------|
+| Arrow IPC | ❌ Not supported | Apache Arrow not browser-compatible |
+| JSON table | ✅ Supported | Only table type available in browser |
+| File server upload | ✅ Supported | HTTP/HTTPS |
+| File server download | ✅ Supported | HTTP/HTTPS |
+| Size threshold | 500KB | Configurable |
+
 ### MicroPython
 
 | Feature | Status | Notes |