Overhaul card-data ingest: filter art cards, segmented cancellable progress

- Exclude Scryfall Art Series cards (layout "art_series") from ingest —
  they aren't playable cards and were polluting search results.
- Replace the coarse per-stage progress text with a byte-accurate,
  weighted multi-segment progress bar (Index / Card data / Printings /
  Indexing) that fills as one continuous bar instead of swapping per
  stage; segment weights are computed from the real download sizes
  reported by Scryfall's bulk-data index (the download responses
  themselves are chunked with no Content-Length to rely on).
- Add a Cancel button, wired through a new CancelToken checked once per
  parsed record so cancellation lands almost instantly.
- Fix a related correctness bug this surfaced: ingest used to delete the
  existing reference.db before writing its replacement, so a cancelled
  or crashed update left the app with no card database at all. It now
  builds into a temp file and only atomically replaces reference.db on
  full success.
- Split the topbar's single "Choose library…" action into separate
  "Open Library…" (existing file) and "New Library…" (save-dialog for a
  new file) buttons.

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

src/api.ts

@@ -54,6 +54,19 @@ export interface Status {
   card_count: number;
 }
 
+export interface IngestStageInfo {
+  id: string;
+  label: string;
+  weight: number; // fraction of total work, 0..1, sums to 1 across all stages
+}
+
+export interface IngestProgress {
+  stage: "index" | "oracle" | "printings" | "optimize" | string;
+  message: string;
+  overall_percent: number; // 0..100 cumulative across all stages
+  stages: IngestStageInfo[];
+}
+
 // --- WUBRG bitmask helpers ------------------------------------------------
 
 export const COLORS: { bit: number; code: string; label: string }[] = [
@@ -76,6 +89,7 @@ export const api = {
   getStatus: () => invoke<Status>("get_status"),
   setLibraryPath: (path: string) => invoke<Status>("set_library_path", { path }),
   updateCardData: () => invoke<Status>("update_card_data"),
+  cancelUpdateCardData: () => invoke<void>("cancel_update_card_data"),
 
   searchCards: (query: string, limit = 20) =>
     invoke<CardRef[]>("search_cards", { query, limit }),