refactor: extract data fixes into dedicated package

internal/database/fixes/20260526_episode_availability_backfill_next_refresh_at.go

@@ -0,0 +1,28 @@
+package fixes
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+)
+
+func init() {
+	Register(Fix{
+		ID: "20260526_episode_availability_backfill_next_refresh_at",
+		Apply: func(ctx context.Context, sqlDB *sql.DB) error {
+			// Old caches could have next_refresh_at NULL (especially for airing shows with missing broadcast metadata),
+			// which can result in "never refresh again" behavior on the server.
+			_, err := sqlDB.ExecContext(ctx, `
+UPDATE episode_availability_cache
+SET next_refresh_at = datetime(CURRENT_TIMESTAMP, '+6 hours'),
+    updated_at = CURRENT_TIMESTAMP
+WHERE next_refresh_at IS NULL;
+`)
+			if err != nil {
+				return fmt.Errorf("backfill episode_availability_cache.next_refresh_at: %w", err)
+			}
+			return nil
+		},
+	})
+}
+

internal/database/fixes/registry.go

@@ -0,0 +1,25 @@
+package fixes
+
+import (
+	"context"
+	"database/sql"
+	"sort"
+)
+
+type Fix struct {
+	ID    string
+	Apply func(ctx context.Context, sqlDB *sql.DB) error
+}
+
+var registered []Fix
+
+func Register(fix Fix) {
+	registered = append(registered, fix)
+}
+
+func All() []Fix {
+	out := append([]Fix(nil), registered...)
+	sort.Slice(out, func(i, j int) bool { return out[i].ID < out[j].ID })
+	return out
+}
+