webui: auto-refresh /props on inference start to resync model metadata (#16784)

* webui: auto-refresh /props on inference start to resync model metadata

- Add no-cache headers to /props and /slots
- Throttle slot checks to 30s
- Prevent concurrent fetches with promise guard
- Trigger refresh from chat streaming for legacy and ModelSelector
- Show dynamic serverWarning when using cached data

* fix: restore proper legacy behavior in webui by using unified /props refresh

Updated assistant message bubbles to show each message's stored model when available,
falling back to the current server model only when the per-message value is missing

When the model selector is disabled, now fetches /props and prioritizes that model name
over chunk metadata, then persists it with the streamed message so legacy mode properly
reflects the backend configuration

* fix: detect first valid SSE chunk and refresh server props once

* fix: removed the slots availability throttle constant and state

* webui: purge ai-generated cruft

* chore: update webui static build

tools/server/webui/src/lib/stores/chat.svelte.ts

@@ -1,6 +1,7 @@
 import { DatabaseStore } from '$lib/stores/database';
 import { chatService, slotsService } from '$lib/services';
 import { config } from '$lib/stores/settings.svelte';
+import { serverStore } from '$lib/stores/server.svelte';
 import { normalizeModelName } from '$lib/utils/model-names';
 import { filterByLeafNodeId, findLeafNode, findDescendantMessages } from '$lib/utils/branching';
 import { browser } from '$app/environment';
@@ -362,9 +363,41 @@ class ChatStore {
 
 		let resolvedModel: string | null = null;
 		let modelPersisted = false;
+		const currentConfig = config();
+		const preferServerPropsModel = !currentConfig.modelSelectorEnabled;
+		let serverPropsRefreshed = false;
+		let updateModelFromServerProps: ((persistImmediately?: boolean) => void) | null = null;
 
-		const recordModel = (modelName: string, persistImmediately = true): void => {
-			const normalizedModel = normalizeModelName(modelName);
+		const refreshServerPropsOnce = () => {
+			if (serverPropsRefreshed) {
+				return;
+			}
+
+			serverPropsRefreshed = true;
+
+			const hasExistingProps = serverStore.serverProps !== null;
+
+			serverStore
+				.fetchServerProps({ silent: hasExistingProps })
+				.then(() => {
+					updateModelFromServerProps?.(true);
+				})
+				.catch((error) => {
+					console.warn('Failed to refresh server props after streaming started:', error);
+				});
+		};
+
+		const recordModel = (modelName: string | null | undefined, persistImmediately = true): void => {
+			const serverModelName = serverStore.modelName;
+			const preferredModelSource = preferServerPropsModel
+				? (serverModelName ?? modelName ?? null)
+				: (modelName ?? serverModelName ?? null);
+
+			if (!preferredModelSource) {
+				return;
+			}
+
+			const normalizedModel = normalizeModelName(preferredModelSource);
 
 			if (!normalizedModel || normalizedModel === resolvedModel) {
 				return;
@@ -388,6 +421,20 @@ class ChatStore {
 			}
 		};
 
+		if (preferServerPropsModel) {
+			updateModelFromServerProps = (persistImmediately = true) => {
+				const currentServerModel = serverStore.modelName;
+
+				if (!currentServerModel) {
+					return;
+				}
+
+				recordModel(currentServerModel, persistImmediately);
+			};
+
+			updateModelFromServerProps(false);
+		}
+
 		slotsService.startStreaming();
 		slotsService.setActiveConversation(assistantMessage.convId);
 
@@ -396,6 +443,9 @@ class ChatStore {
 			{
 				...this.getApiOptions(),
 
+				onFirstValidChunk: () => {
+					refreshServerPropsOnce();
+				},
 				onChunk: (chunk: string) => {
 					streamedContent += chunk;
 					this.setConversationStreaming(