feat(kon): add first-run hardware probe and model recommendation wizard

- New probe_system command: returns RAM, CPU, OS info
- New rank_models command: scores models against detected hardware
- FirstRunPage.svelte: hardware summary, ranked model list with
  "Recommended" badge on top pick, download progress bar, skip option
- First-run detection in layout: checks list_models + list_parakeet_models,
  shows wizard if both empty
- Sidebar hidden during first-run for clean wizard experience
- clippy clean

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/routes/+layout.svelte

@@ -1,6 +1,7 @@
 <script>
   import "../app.css";
-  import { onDestroy } from "svelte";
+  import { onMount, onDestroy } from "svelte";
+  import { invoke } from "@tauri-apps/api/core";
   import Sidebar from "$lib/Sidebar.svelte";
   import TaskSidebar from "$lib/components/TaskSidebar.svelte";
   import Titlebar from "$lib/components/Titlebar.svelte";
@@ -66,6 +67,19 @@
     document.documentElement.style.setProperty("--font-size-transcript", `${settings.fontSize}px`);
   });
 
+  // First-run detection: check if any models are downloaded
+  onMount(async () => {
+    try {
+      const whisper = await invoke("list_models");
+      const parakeet = await invoke("list_parakeet_models");
+      if (whisper.length === 0 && parakeet.length === 0) {
+        page.current = "first-run";
+      }
+    } catch {
+      // If commands fail, skip first-run check
+    }
+  });
+
   onDestroy(() => {
     if (registeredHotkey) {
       import("@tauri-apps/plugin-global-shortcut")
@@ -87,11 +101,13 @@
 <div class="flex flex-col h-screen w-screen overflow-hidden grain">
   <Titlebar />
   <div class="flex flex-1 min-h-0">
-    <Sidebar />
+    {#if page.current !== "first-run"}
+      <Sidebar />
+    {/if}
     <div class="flex-1 overflow-hidden bg-bg">
       {@render children()}
     </div>
-    {#if page.taskSidebarOpen}
+    {#if page.taskSidebarOpen && page.current !== "first-run"}
       <TaskSidebar />
     {/if}
   </div>