agent: Show warning for image context pill if model doesn't support images (#31848)

Closes #31781

Currently we don't any warning or error if the image is not supported by
the current model in selected in the agent panel which leads for users
to think it's supported as there is no visual feedback provided by zed.
This PR adds a warning on image context pill to show warning when the
model doesn't support it.

| Before | After |
|--------|-------|
| <img width="374" alt="image"
src="https://github.com/user-attachments/assets/da659fb6-d5da-4c53-8878-7a1c4553f168"
/> | <img width="442" alt="image"
src="https://github.com/user-attachments/assets/0f23d184-6095-47e2-8f2b-0eac64a0942e"
/> |

Release Notes:

- Show warning for image context pill in agent panel when selected model
doesn't support images.

---------

Signed-off-by: Umesh Yadav <git@umesh.dev>
Co-authored-by: Bennet Bo Fenner <bennetbo@gmx.de>

crates/agent/src/active_thread.rs

@@ -1,4 +1,3 @@
-use crate::AgentPanel;
 use crate::context::{AgentContextHandle, RULES_ICON};
 use crate::context_picker::{ContextPicker, MentionLink};
 use crate::context_store::ContextStore;
@@ -13,6 +12,7 @@ use crate::tool_use::{PendingToolUseStatus, ToolUse};
 use crate::ui::{
     AddedContext, AgentNotification, AgentNotificationEvent, AnimatedLabel, ContextPill,
 };
+use crate::{AgentPanel, ModelUsageContext};
 use agent_settings::{AgentSettings, NotifyWhenAgentWaiting};
 use anyhow::Context as _;
 use assistant_tool::ToolUseStatus;
@@ -1348,6 +1348,7 @@ impl ActiveThread {
                 Some(self.text_thread_store.downgrade()),
                 context_picker_menu_handle.clone(),
                 SuggestContextKind::File,
+                ModelUsageContext::Thread(self.thread.clone()),
                 window,
                 cx,
             )
@@ -1826,9 +1827,10 @@ impl ActiveThread {
 
         // Get all the data we need from thread before we start using it in closures
         let checkpoint = thread.checkpoint_for_message(message_id);
+        let configured_model = thread.configured_model().map(|m| m.model);
         let added_context = thread
             .context_for_message(message_id)
-            .map(|context| AddedContext::new_attached(context, cx))
+            .map(|context| AddedContext::new_attached(context, configured_model.as_ref(), cx))
             .collect::<Vec<_>>();
 
         let tool_uses = thread.tool_uses_for_message(message_id, cx);