Add card USD pricing and a deck maybeboard

Prices come from Scryfall's prices.usd on printings, shown as a hover badge
on card tiles. The price is picked independently of whichever printing
supplies the display image (the cheapest known price across all printings),
since the display printing is often a promo/variant with no listed price.

The maybeboard lets a deck track cards under consideration without counting
them in deck analysis stats or library assignment totals. Cards move between
mainboard and maybeboard via a per-card toggle; maybeboarding the commander
clears commander status.

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

src-tauri/src/commands.rs

@@ -207,10 +207,11 @@ pub fn set_deck_card(
     oracle_id: String,
     quantity: i64,
     is_commander: bool,
+    is_maybeboard: bool,
 ) -> Res<()> {
     let s = db.lock().unwrap();
     s.catalog()?
-        .set_deck_card(deck_id, &oracle_id, quantity, is_commander)
+        .set_deck_card(deck_id, &oracle_id, quantity, is_commander, is_maybeboard)
         .map_err(|e| e.to_string())
 }