Allow using URL Params to jumpstart NewChat with a given message.

For example,
```
https://localhost:5173/#/chat/new?message=hello
```

This will start a new chat and then send the message out to kickoff the session.

Issue: #418

Author: lazywei

src/lib/NewChat.svelte

@@ -1,20 +1,41 @@
 <script lang="ts">
-  import { querystring } from 'svelte-spa-router'
-  import { addChat, setChatSettingValueByKey } from './Storage.svelte'
-  import { replace } from 'svelte-spa-router'
-  import { getProfile, restartProfile } from './Profiles.svelte'
-  import { getChatDefaults, hasChatSetting } from './Settings.svelte'
+  import { querystring } from "svelte-spa-router";
+  import {
+    addChat,
+    addMessage,
+    setChatSettingValueByKey,
+    submitExitingPromptsNow,
+  } from "./Storage.svelte";
+  import { replace } from "svelte-spa-router";
+  import { getProfile, restartProfile } from "./Profiles.svelte";
+  import { getChatDefaults, hasChatSetting } from "./Settings.svelte";
+  import { v4 as uuidv4 } from "uuid";
+  import { type Message } from "./Types.svelte";
 
   // Create the new chat instance then redirect to it
 
-  const urlParams: URLSearchParams = new URLSearchParams($querystring)
-  const chatId = urlParams.has('p') ? addChat(getProfile(urlParams.get('p') || '')) : addChat()
-  Object.keys(getChatDefaults()).forEach(k => {
+  const urlParams: URLSearchParams = new URLSearchParams($querystring);
+  const chatId = urlParams.has("p")
+    ? addChat(getProfile(urlParams.get("p") || ""))
+    : addChat();
+  Object.keys(getChatDefaults()).forEach((k) => {
     if (urlParams.has(k) && hasChatSetting(k as any)) {
-      setChatSettingValueByKey(chatId, k as any, urlParams.get(k))
+      setChatSettingValueByKey(chatId, k as any, urlParams.get(k));
     }
-  })
-  
-  restartProfile(chatId)
-  replace(`/chat/${chatId}`)
+  });
+
+  restartProfile(chatId);
+  const messageContent = urlParams.get("message");
+  if (messageContent !== null) {
+    const uuid = uuidv4();
+    const inputMessage: Message = {
+      role: "user",
+      content: messageContent,
+      uuid,
+    };
+    addMessage(chatId, inputMessage);
+    $submitExitingPromptsNow = true;
+  }
+
+  replace(`/chat/${chatId}`);
 </script>