Shared card filter panel: News set browser gets every Library filter

Extract the filter fields and LibraryFilter-building state into
src/cardFilter.tsx (CardFilterPanel + useCardFilter) and use it in the
Library, Card Search and News set browser, replacing three diverging
copies. search_reference now honors in_deck/location too, so every
filter works in every tab.

Closes #13

src/components.tsx

@@ -2181,16 +2181,12 @@ export function CardCriteriaFields({
   value: c,
   onChange,
   hideNotOwned,
-  showSpares,
 }: {
   value: CardCriteria;
   onChange: (patch: Partial<CardCriteria>) => void;
   /** Omit the "Not owned" toggle — for the Library tab, which already shows
    *  nothing but owned cards, so the filter would just be a no-op there. */
   hideNotOwned?: boolean;
-  /** Offer the "spare copies" toggle — a question about your collection, so
-   *  it belongs in the Library rather than in a search of every card. */
-  showSpares?: boolean;
 }) {
   const toggleRarity = (key: string) =>
     onChange({
@@ -2296,15 +2292,13 @@ export function CardCriteriaFields({
             on={c.vanillaOnly}
             onToggle={() => onChange({ vanillaOnly: !c.vanillaOnly })}
           />
-          {showSpares && (
-            <IconToggle
-              icon={ICON_SPARE}
-              label="Only spare copies"
-              hint="Cards you own more copies of than your decks use — free for a trade or a new deck. Maybeboards don't count."
-              on={c.sparesOnly}
-              onToggle={() => onChange({ sparesOnly: !c.sparesOnly })}
-            />
-          )}
+          <IconToggle
+            icon={ICON_SPARE}
+            label="Only spare copies"
+            hint="Cards you own more copies of than your decks use — free for a trade or a new deck. Maybeboards don't count."
+            on={c.sparesOnly}
+            onToggle={() => onChange({ sparesOnly: !c.sparesOnly })}
+          />
           {!hideNotOwned && (
             <IconToggle
               icon={ICON_PACKAGE}