refactor: use canonical token-to-symbol maps for market lookup

Build canonical spot/future token maps with quote priority, unify cache refresh scheduling, and switch resolver/token tests to map-based token lookups.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

internal/data/market/trading_pairs_test.go

@@ -0,0 +1,41 @@
+package market
+
+import "testing"
+
+func TestSelectCanonicalSymbolByQuotePriority(t *testing.T) {
+	pairs := []string{"DOGEFDUSD", "DOGEUSDC", "DOGEUSDT"}
+	got := selectCanonicalSymbolByQuotePriority("DOGE", pairs)
+	if got != "DOGEUSDT" {
+		t.Fatalf("expected DOGEUSDT, got %q", got)
+	}
+}
+
+func TestSelectCanonicalSymbolByQuotePriority_FallbackOrder(t *testing.T) {
+	pairs := []string{"DOGEFDUSD", "DOGEUSDC"}
+	got := selectCanonicalSymbolByQuotePriority("DOGE", pairs)
+	if got != "DOGEUSDC" {
+		t.Fatalf("expected DOGEUSDC, got %q", got)
+	}
+}
+
+func TestSelectCanonicalSymbolByQuotePriority_NoPreferredQuote(t *testing.T) {
+	pairs := []string{"DOGEBUSD"}
+	got := selectCanonicalSymbolByQuotePriority("DOGE", pairs)
+	if got != "DOGEBUSD" {
+		t.Fatalf("expected DOGEBUSD, got %q", got)
+	}
+}
+
+func TestNormalizeFutureToken_AppliesOverride(t *testing.T) {
+	got := normalizeFutureToken("LUNA2")
+	if got != "LUNA" {
+		t.Fatalf("expected LUNA, got %q", got)
+	}
+}
+
+func TestNormalizeFutureToken_NoOverride(t *testing.T) {
+	got := normalizeFutureToken("PEPE")
+	if got != "PEPE" {
+		t.Fatalf("expected PEPE, got %q", got)
+	}
+}