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-tauri/src/lib.rs

@@ -70,6 +70,9 @@ pub fn run() {
             commands::windows::open_viewer_window,
             // Clipboard
             commands::clipboard::copy_to_clipboard,
+            // Hardware
+            commands::hardware::probe_system,
+            commands::hardware::rank_models,
             // LLM stubs
             commands::llm::download_llm_model,
             commands::llm::check_llm_model,