Layout and axis operations implementations
Single Responsibility: Handle twin axes, subplots, reference lines, tick configuration, aspect ratio, and tight layout operations. Extracted from fortplot_figure_core_impl to maintain file size compliance.
── Twin axis operations ──────────────────────────────────────────
── Subplot operations ────────────────────────────────────────────
── Reference line operations ─────────────────────────────────────
── Tick operations ───────────────────────────────────────────────
── Aspect ratio ──────────────────────────────────────────────────
── Layout ────────────────────────────────────────────────────────