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>

server/importer/simplenote.go

@@ -0,0 +1,126 @@
+// Package importer reads Simplenote export archives into the store.
+package importer
+
+import (
+	"archive/zip"
+	"crypto/sha256"
+	"encoding/json"
+	"fmt"
+	"io"
+	"strings"
+	"time"
+
+	"tefter/server/store"
+)
+
+// Verified against a real export (2026): the zip contains source/notes.json with
+// {activeNotes: [...], trashedNotes: [...]}; each note has id, content,
+// creationDate, lastModified (ISO 8601) and optionally tags. There is no
+// `markdown` field in current exports.
+type snNote struct {
+	ID           string   `json:"id"`
+	Content      string   `json:"content"`
+	CreationDate string   `json:"creationDate"`
+	LastModified string   `json:"lastModified"`
+	Tags         []string `json:"tags"`
+}
+
+type snExport struct {
+	ActiveNotes  []snNote `json:"activeNotes"`
+	TrashedNotes []snNote `json:"trashedNotes"`
+}
+
+type Summary struct {
+	Imported int `json:"imported"`
+	Skipped  int `json:"skipped"`
+	Trashed  int `json:"trashed"`
+}
+
+func (s Summary) String() string {
+	return fmt.Sprintf("imported %d, skipped %d duplicates, %d trashed", s.Imported, s.Skipped, s.Trashed)
+}
+
+func parseTime(iso string, fallback time.Time) int64 {
+	if t, err := time.Parse(time.RFC3339, iso); err == nil {
+		return t.UnixMilli()
+	}
+	return fallback.UnixMilli()
+}
+
+// ImportZip imports a Simplenote export zip (as a reader) into st. Idempotent:
+// notes are deduped by Simplenote id kept in the source_id column.
+func ImportZip(st *store.Store, r io.ReaderAt, size int64) (Summary, error) {
+	var sum Summary
+	zr, err := zip.NewReader(r, size)
+	if err != nil {
+		return sum, fmt.Errorf("open zip: %w", err)
+	}
+
+	var data []byte
+	for _, f := range zr.File {
+		if f.Name == "source/notes.json" || strings.HasSuffix(f.Name, "/notes.json") || f.Name == "notes.json" {
+			rc, err := f.Open()
+			if err != nil {
+				return sum, err
+			}
+			data, err = io.ReadAll(rc)
+			rc.Close()
+			if err != nil {
+				return sum, err
+			}
+			break
+		}
+	}
+	if data == nil {
+		return sum, fmt.Errorf("notes.json not found in archive (expected source/notes.json)")
+	}
+
+	var exp snExport
+	if err := json.Unmarshal(data, &exp); err != nil {
+		return sum, fmt.Errorf("parse notes.json: %w", err)
+	}
+
+	now := time.Now()
+	doImport := func(notes []snNote, deleted bool) error {
+		for _, sn := range notes {
+			if sn.ID == "" {
+				// No id to dedupe on — synthesize one from content+creation date.
+				sn.ID = fmt.Sprintf("synth-%x", contentHash(sn))
+			}
+			n := store.Note{
+				Content:    strings.ReplaceAll(sn.Content, "\r\n", "\n"),
+				Tags:       sn.Tags,
+				CreatedAt:  parseTime(sn.CreationDate, now),
+				ModifiedAt: parseTime(sn.LastModified, now),
+				Deleted:    deleted,
+			}
+			inserted, err := st.UpsertImported("simplenote:"+sn.ID, n)
+			if err != nil {
+				return err
+			}
+			if inserted {
+				if deleted {
+					sum.Trashed++
+				} else {
+					sum.Imported++
+				}
+			} else {
+				sum.Skipped++
+			}
+		}
+		return nil
+	}
+
+	if err := doImport(exp.ActiveNotes, false); err != nil {
+		return sum, err
+	}
+	if err := doImport(exp.TrashedNotes, true); err != nil {
+		return sum, err
+	}
+	return sum, nil
+}
+
+func contentHash(sn snNote) []byte {
+	h := sha256.Sum256([]byte(sn.CreationDate + "\x00" + sn.Content))
+	return h[:16]
+}