agent: Support pasting images as context (#29177)

https://github.com/user-attachments/assets/d6a27b05-3590-4f40-a820-f6f99f6bd581

Release Notes:

- agent: Added support for pasting images as context

---------

Co-authored-by: Danilo Leal <daniloleal09@gmail.com>

crates/language_model/src/request.rs

@@ -32,7 +32,14 @@ impl std::fmt::Debug for LanguageModelImage {
 const ANTHROPIC_SIZE_LIMT: f32 = 1568.;
 
 impl LanguageModelImage {
-    pub fn from_image(data: Image, cx: &mut App) -> Task<Option<Self>> {
+    pub fn empty() -> Self {
+        Self {
+            source: "".into(),
+            size: size(DevicePixels(0), DevicePixels(0)),
+        }
+    }
+
+    pub fn from_image(data: Arc<Image>, cx: &mut App) -> Task<Option<Self>> {
         cx.background_spawn(async move {
             match data.format() {
                 gpui::ImageFormat::Png