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/SegmentedButton.svelte

@@ -0,0 +1,18 @@
+<script>
+  let { options = [], value = $bindable(""), size = "default" } = $props();
+</script>
+
+<div class="inline-flex bg-bg-elevated rounded-[10px] p-[3px] gap-[2px]">
+  {#each options as option}
+    <button
+      class="rounded-lg font-medium
+        {size === 'small' ? 'px-2.5 py-1 text-[11px]' : 'px-3.5 py-[6px] text-[12px]'}
+        {value === option
+          ? 'bg-accent text-white shadow-[0_1px_4px_rgba(232,168,124,0.3)]'
+          : 'text-text-secondary hover:text-text hover:bg-hover'}"
+      onclick={() => value = option}
+    >
+      {option}
+    </button>
+  {/each}
+</div>