v1.0.0

The 1.0 release. The public API is now stable and committed to under Semantic
Versioning: Render, AppendRender, Options, Palette (+ Validate), the
Variant set (+ Variants, ParseVariant, String), and the ColorProfile
enum. No exported identifier will be renamed, removed, or retyped before a
2.0.0; new variants, options, profiles, and methods may still be added, since
those are additive. The core contract is unchanged and now permanent: Render
and AppendRender are pure over their inputs and emit exactly h lines of
exactly w visible cells, never erroring or panicking on any Options — a
malformed Palette degrades to documented fallbacks, and Palette.Validate is
the opt-in check. The surface was validated against its real downstream consumer
(atrium bumped to v0.3.0 with zero code changes) and given a final last-look
review before freezing; see docs/api-review-v1.0.md.

Added

• fresco.Aurora — a fifth splash variant: northern-lights curtains that drift
  slowly sideways over dark sky and snake as they go, the hue sliding warm→cool with
  altitude. An absolute field like Rain and Ripple (a bigger pane shows more
  sky), shaded at lumRange 0.75 so the filament cores keep the density ramp while
  the soft halo rides the colour. Registered in Variants(), ParseVariant, and
  the rotation.