Function analyze 

pub fn analyze(
    data: &LoadedData,
    spatial: &SpatialAnalysis,
    temporal: &TemporalAnalysis,
    measured: Option<&MeasuredEncoding>,
) -> Result<DensityAnalysis>

Analyze tile density across the recommended zoom range.

Models the real build: at every zoom in the recommended [min_zoom, max_zoom] range each feature lands in its containing (x, y) tile, split by fixed --temporal-bucket-sized time buckets (the recommended bucket from the temporal analysis). This is the cut stt-build actually makes, so predicted tile counts and sizes track a real build.

When a measured sample encoding is present, size estimates use its real encoder bytes/feature and zstd ratio; otherwise the per-feature formula estimate with an assumed 3x compression ratio is the fallback.