Generate portrayal assets

tile57_bake_assets produces all portrayal assets in memory — colour tables, line styles, and the sprite / area-fill pattern atlases — from the library's embedded catalogue (catalog_dir NULL/"") or an on-disk PortrayalCatalog. Every non-NULL buffer is owned by the library; release the whole struct with tile57_assets_free.

typedef struct {
    uint8_t *colortables;  size_t colortables_len;
    uint8_t *linestyles;   size_t linestyles_len;
    uint8_t *sprite_json;  size_t sprite_json_len;   uint8_t *sprite_png;  size_t sprite_png_len;
    uint8_t *pattern_json; size_t pattern_json_len;  uint8_t *pattern_png; size_t pattern_png_len;
} tile57_assets;

tile57_status tile57_bake_assets(const char *catalog_dir, tile57_assets *out,
                                 tile57_error *err);
void tile57_assets_free(tile57_assets *out);

tile57_bake_sprite_mln is a focused variant that fills only the sprite_json / sprite_png fields with a MapLibre sprite-mln atlas: every S-101 symbol packed into one PNG, each atlas cell centered on its symbol's pivot, plus a JSON index of {name: {x, y, width, height, pixelRatio}}. A GPU host loads this atlas once and draws point symbols and area patterns as textured quads by name — the atlas the host-surface draw_sprite/draw_pattern callbacks hand back. tile57_bake_glyph_sdf is its text counterpart: an RGBA signed-distance-field atlas of the label font, for a host that draws text as SDF quads. Free either with tile57_assets_free as above.

tile57_status tile57_bake_sprite_mln(const char *catalog_dir, tile57_assets *out,
                                     tile57_error *err);
tile57_status tile57_bake_glyph_sdf(tile57_assets *out, tile57_error *err);