test(repos): add SQL integration tests for 17 untested repo files

Add 148 integration tests exercising actual SQL against PostgreSQL for
all previously untested repository files. Includes 6 new fixture helpers
in testhelpers_db.go and CI PostgreSQL service configuration.

Discovered and documented existing RecordPurchase SQL bug (ambiguous
column reference in ON CONFLICT clause).

server/channelserver/repo_misc_test.go

@@ -0,0 +1,110 @@
+package channelserver
+
+import (
+	"testing"
+
+	"github.com/jmoiron/sqlx"
+)
+
+func setupMiscRepo(t *testing.T) (*MiscRepository, *sqlx.DB) {
+	t.Helper()
+	db := SetupTestDB(t)
+	repo := NewMiscRepository(db)
+	t.Cleanup(func() { TeardownTestDB(t, db) })
+	return repo, db
+}
+
+func TestRepoMiscUpsertTrendWeapon(t *testing.T) {
+	repo, db := setupMiscRepo(t)
+
+	if err := repo.UpsertTrendWeapon(100, 1); err != nil {
+		t.Fatalf("UpsertTrendWeapon failed: %v", err)
+	}
+
+	var count int
+	if err := db.QueryRow("SELECT count FROM trend_weapons WHERE weapon_id=100").Scan(&count); err != nil {
+		t.Fatalf("Verification query failed: %v", err)
+	}
+	if count != 1 {
+		t.Errorf("Expected count=1, got: %d", count)
+	}
+}
+
+func TestRepoMiscUpsertTrendWeaponIncrement(t *testing.T) {
+	repo, db := setupMiscRepo(t)
+
+	if err := repo.UpsertTrendWeapon(100, 1); err != nil {
+		t.Fatalf("First UpsertTrendWeapon failed: %v", err)
+	}
+	if err := repo.UpsertTrendWeapon(100, 1); err != nil {
+		t.Fatalf("Second UpsertTrendWeapon failed: %v", err)
+	}
+
+	var count int
+	if err := db.QueryRow("SELECT count FROM trend_weapons WHERE weapon_id=100").Scan(&count); err != nil {
+		t.Fatalf("Verification query failed: %v", err)
+	}
+	if count != 2 {
+		t.Errorf("Expected count=2 after upsert, got: %d", count)
+	}
+}
+
+func TestRepoMiscGetTrendWeaponsEmpty(t *testing.T) {
+	repo, _ := setupMiscRepo(t)
+
+	weapons, err := repo.GetTrendWeapons(1)
+	if err != nil {
+		t.Fatalf("GetTrendWeapons failed: %v", err)
+	}
+	if len(weapons) != 0 {
+		t.Errorf("Expected 0 weapons, got: %d", len(weapons))
+	}
+}
+
+func TestRepoMiscGetTrendWeaponsOrdering(t *testing.T) {
+	repo, _ := setupMiscRepo(t)
+
+	// Insert weapons with different counts
+	for i := 0; i < 3; i++ {
+		if err := repo.UpsertTrendWeapon(uint16(100+i), 1); err != nil {
+			t.Fatalf("UpsertTrendWeapon failed: %v", err)
+		}
+	}
+	// Give weapon 101 more uses
+	if err := repo.UpsertTrendWeapon(101, 1); err != nil {
+		t.Fatalf("UpsertTrendWeapon failed: %v", err)
+	}
+	if err := repo.UpsertTrendWeapon(101, 1); err != nil {
+		t.Fatalf("UpsertTrendWeapon failed: %v", err)
+	}
+
+	weapons, err := repo.GetTrendWeapons(1)
+	if err != nil {
+		t.Fatalf("GetTrendWeapons failed: %v", err)
+	}
+	if len(weapons) != 3 {
+		t.Fatalf("Expected 3 weapons, got: %d", len(weapons))
+	}
+	// First should be the one with highest count (101 with count=3)
+	if weapons[0] != 101 {
+		t.Errorf("Expected first weapon=101 (highest count), got: %d", weapons[0])
+	}
+}
+
+func TestRepoMiscGetTrendWeaponsLimit3(t *testing.T) {
+	repo, _ := setupMiscRepo(t)
+
+	for i := 0; i < 5; i++ {
+		if err := repo.UpsertTrendWeapon(uint16(100+i), 1); err != nil {
+			t.Fatalf("UpsertTrendWeapon failed: %v", err)
+		}
+	}
+
+	weapons, err := repo.GetTrendWeapons(1)
+	if err != nil {
+		t.Fatalf("GetTrendWeapons failed: %v", err)
+	}
+	if len(weapons) != 3 {
+		t.Errorf("Expected max 3 weapons, got: %d", len(weapons))
+	}
+}