feat(kon): scaffold hybrid modular workspace

- Cargo workspace with 6 domain crates: core, audio, transcription, ai-formatting, storage, cloud-providers
- Minimal Tauri shell (lib.rs + main.rs) with plugin registration
- Svelte 5 frontend copied from Ramble v0.2
- All crates compile as empty stubs
- App identifier: uk.co.corbel.kon

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

src/lib/components/Titlebar.svelte

@@ -0,0 +1,70 @@
+<script>
+  import { getCurrentWindow } from "@tauri-apps/api/window";
+
+  let maximised = $state(false);
+
+  async function handleMinimise() {
+    await getCurrentWindow().minimize();
+  }
+
+  async function handleMaximise() {
+    await getCurrentWindow().toggleMaximize();
+    maximised = await getCurrentWindow().isMaximized();
+  }
+
+  async function handleClose() {
+    await getCurrentWindow().hide();
+  }
+
+  function handleDragStart(e) {
+    if (e.button !== 0) return;
+    if (e.target.closest("button")) return;
+    getCurrentWindow().startDragging();
+  }
+
+  // Track maximise state
+  $effect(() => {
+    let unlisten;
+    getCurrentWindow().onResized(async () => {
+      maximised = await getCurrentWindow().isMaximized();
+    }).then((fn) => unlisten = fn);
+    return () => unlisten?.();
+  });
+</script>
+
+<div
+  class="flex items-center h-[32px] select-none bg-sidebar border-b border-border-subtle"
+  onmousedown={handleDragStart}
+  data-tauri-drag-region
+>
+  <!-- Left spacer: aligns with sidebar width -->
+  <div class="w-[210px] min-w-[210px]" data-tauri-drag-region></div>
+
+  <!-- Centre: drag area -->
+  <div class="flex-1" data-tauri-drag-region></div>
+
+  <!-- Window controls -->
+  <div class="flex items-center h-full">
+    <button class="titlebar-btn hover:bg-hover" onclick={handleMinimise} aria-label="Minimise">
+      <svg class="w-3 h-3" viewBox="0 0 12 12">
+        <rect y="5" width="12" height="1.5" rx="0.5" fill="currentColor" />
+      </svg>
+    </button>
+    <button class="titlebar-btn hover:bg-hover" onclick={handleMaximise} aria-label="Maximise">
+      {#if maximised}
+        <svg class="w-3 h-3" viewBox="0 0 12 12">
+          <path d="M3 1h8v8h-2v2H1V3h2V1zm1 1v1h5v5h1V2H4zm-2 2v6h6V4H2z" fill="currentColor" />
+        </svg>
+      {:else}
+        <svg class="w-3 h-3" viewBox="0 0 12 12">
+          <rect x="1" y="1" width="10" height="10" rx="1" fill="none" stroke="currentColor" stroke-width="1.5" />
+        </svg>
+      {/if}
+    </button>
+    <button class="titlebar-btn hover:bg-danger/20 hover:text-danger" onclick={handleClose} aria-label="Close">
+      <svg class="w-3 h-3" viewBox="0 0 12 12">
+        <path d="M1 1l10 10M11 1L1 11" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" />
+      </svg>
+    </button>
+  </div>
+</div>