Deck chips open their deck

Deck-name chips in the Library, Card Search and the card preview modal are
now buttons (DeckChip) that open that deck in the Decks tab — on mobile,
straight to its building screen. App provides the open-deck callback via
context and hands the deck id to DeckView.

Closes #19

src/styles.css

@@ -1671,6 +1671,19 @@ tbody tr:hover {
   color: var(--text);
   margin-right: 4px;
 }
+/* A deck chip that opens its deck (see `DeckChip`): keeps the chip's own
+   look rather than the global button's, plus a hover cue. */
+.deck-chip-link {
+  line-height: inherit;
+  cursor: pointer;
+}
+.deck-chip.deck-chip-link {
+  font-weight: inherit;
+}
+.deck-chip-link:hover {
+  border-color: var(--accent);
+  color: var(--text-strong);
+}
 
 /* ============================================================
    Bulk-selection action bar (Library tab)