Add deck synergy suggestions, a responsive deck layout, and undoable library bulk-add

Suggestion scoring is fully offline (tribal/mechanic/archetype/mana-base
signals derived at ingest, no external synergy database), with an "unusual
picks" mode that surfaces underappreciated cards instead of staples. The
deck page's top panels now use a CSS grid so wide windows don't waste
horizontal space. Library's bulk add-to-deck can clobber existing deck
quantities, so it now offers an undo (snackbar + command palette, the
latter with no timeout) that restores each card's prior state exactly.

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

src/api.ts

@@ -52,6 +52,19 @@ export interface LibraryImportResult {
   unresolved: string[];
 }
 
+export interface SynergyReason {
+  category: string; // "Tribal" | "Mechanic" | "Archetype" | "Mana base"
+  detail: string;
+}
+
+export interface CardSuggestion {
+  card: CardRef;
+  quantity_owned: number;
+  score: number;
+  reasons: SynergyReason[];
+  edhrec_rank: number | null;
+}
+
 export interface LibraryFilter {
   text?: string | null;
   colors_exact?: number | null;
@@ -186,6 +199,8 @@ export const api = {
     isMaybeboard = false,
   ) => invoke<void>("set_deck_card", { deckId, oracleId, quantity, isCommander, isMaybeboard }),
   deckContents: (deckId: number) => invoke<DeckEntry[]>("deck_contents", { deckId }),
+  suggestCards: (deckId: number, offset = 0, unusual = false) =>
+    invoke<CardSuggestion[]>("suggest_cards", { deckId, offset, unusual }),
   cardDecks: (oracleId: string) => invoke<Deck[]>("card_decks", { oracleId }),
 
   exportDeck: (deckId: number, path: string) => invoke<void>("export_deck", { deckId, path }),