Implement Tefter per SPEC.md: NV-style notes with server, sync, PWA, desktop

- frontend/: Svelte 4 + TS + Vite app — omnibar (search-and-create), ranked
  diacritic-insensitive filtering, CodeMirror 6 markdown editor with 400ms
  autosave, marked+DOMPurify preview with [[wiki-links]], tag filter, undo
  toast, light/dark, narrow-screen stacked layout, IndexedDB store, pull-then-
  push sync engine with conflict handling, versioned cache-first service
  worker + manifest (installable PWA)
- server/: tefterd — Go stdlib HTTP + modernc.org/sqlite, /api/v1 sync API
  (changes/batch/health/import), SHA-256 hashed bearer token, LWW-with-
  conflict-copies push rules, subcommands: init, token rotate, import
  simplenote, compact, backup (VACUUM INTO); embeds the frontend bundle
- desktop/: Wails v2 shell — single instance, hide-to-tray (fyne systray),
  global Ctrl+Shift+Space hotkey, quit-on-close flag
- Simplenote import (CLI + web upload), idempotent via source_id dedupe;
  verified against a real 242-note export
- Makefile (frontend/server/server-all/desktop/test), GitHub release workflow,
  README with systemd/Caddy/backup docs

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/ui/Toast.svelte

@@ -0,0 +1,55 @@
+<script lang="ts">
+  import { createEventDispatcher } from 'svelte';
+
+  export let message = '';
+  export let actionLabel = '';
+  export let onAction: () => void = () => {};
+
+  const dispatch = createEventDispatcher<{ done: void }>();
+
+  function act() {
+    onAction();
+    dispatch('done');
+  }
+</script>
+
+<div class="toast" role="status">
+  <span>{message}</span>
+  {#if actionLabel}
+    <button on:click={act}>{actionLabel}</button>
+  {/if}
+</div>
+
+<style>
+  .toast {
+    position: fixed;
+    bottom: 18px;
+    left: 50%;
+    transform: translateX(-50%);
+    z-index: 50;
+    display: flex;
+    align-items: center;
+    gap: 14px;
+    background: var(--fg);
+    color: var(--bg);
+    padding: 9px 16px;
+    border-radius: 8px;
+    font-size: 14px;
+    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.25);
+    animation: rise 0.15s ease-out;
+  }
+  .toast button {
+    color: var(--mark-bg);
+    font-weight: 600;
+  }
+  @keyframes rise {
+    from {
+      opacity: 0;
+      transform: translateX(-50%) translateY(8px);
+    }
+    to {
+      opacity: 1;
+      transform: translateX(-50%) translateY(0);
+    }
+  }
+</style>