ui: improve manual model load and cancel (#847)

- When a model is manually loaded show a cancel buttton and a queued
status
- Implement cancellation in scheduler.Scheduler interface and FIFO
scheduler
- Add cache bust query parameter to bypass browser cache

Fixes #844

ui-svelte/src/stores/api.ts

@@ -176,15 +176,19 @@ export async function unloadSingleModel(model: string): Promise<void> {
   }
 }
 
-export async function loadModel(model: string): Promise<void> {
+export async function loadModel(model: string, signal?: AbortSignal): Promise<void> {
   try {
-    const response = await fetch(`/upstream/${model}/`, {
+    const response = await fetch(`/upstream/${model}/?_=${Date.now()}`, {
       method: "GET",
+      signal,
     });
     if (!response.ok) {
       throw new Error(`Failed to load model: ${response.status}`);
     }
   } catch (error) {
+    if (error instanceof DOMException && error.name === "AbortError") {
+      return;
+    }
     console.error("Failed to load model:", error);
     throw error;
   }