feat(simulation): T-1125/T-1126 coastline invention — two-tier character model, shared invent_primitives, Marine vegetation

T-1125: new atlas/coast_invention.rs — BodyCoastEnvelope (tier 1: erosion
maturity derived hydro×atmo, tectonic energy; D-240 stands, no orbital
inputs) + coast_character_at (tier 2: latitude, glaciation fjord response,
local wetness, seeded 100-400 km heterogeneity field). C1 multi-octave
warp ~16-262 km, sub-pixel cap 0.75 px, salted stream isolated from
terrain scatter and climate edge-fuzz.

district_profile: shared invent_primitives front-half (warped envelope
sampling + slope-independent scatter floor + shoreline carving) wired
into BOTH derive_district and derive_district_profile — the batch path's
scatter-free area-mean aggregate is replaced by an invented centre-point
sample of the same continuous field, making silent path divergence
structurally impossible.

T-1126: VegetationClass::Marine appended at discriminant 6, verdict
morphology-derived (open_water from OpenOcean|Lake — no fourth ocean
threshold); airless precedence preserved. voxel.rs exhaustive-match arm
documented unreachable (WaterBody owns ocean districts).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

server/src/atlas/mod.rs

@@ -12,6 +12,7 @@ pub mod body_world_state;
 pub mod cascade;
 pub mod chunk_context;
 pub mod city_context_reader;
+pub mod coast_invention;
 pub mod detail_scatter;
 pub mod district_mix;
 pub mod district_profile;