feat(simulation): atlas proxy layers + data-delivery endpoints (T-960, T-949)

T-960: RoadGraphLayer (L2 edges/junctions, MaintenanceAuthority, rail flag, named routes) + SettlementLayer (name/position/size-class/is_capital/is_port from T-955 placements) as new Option fields on AtlasLayerResponse — T-1046 precedent; layer_proxy doc comment corrected (cascade runs through RoadGraph, client up_to ignored). T-949: new StarMapRequest/StarMapResponse (raw JSON passthrough of the star_map_data.json bake) + CityNamesRequest/CityNamesResponse (atlas_city_names via CityContextReader) with defense-in-depth Sol exclusion (GJ-0 system id OR settlement_wave='origin', D-236). Inbound demux extended with mandatory boolean discriminator fields (serde ignores unknown fields — optional-shape sniffing would be ambiguous); AtlasLayerRequest unchanged. SimBridge trait +2 methods, implemented on TcpBridge + LocalBridge. CityPlacement/CityRecord gained name/population/is_capital (BodyWorldState cache-hit path stays DB-free). ~30 new unit tests incl. demux disambiguation + Sol branches; gen_fixtures extended for road/settlement samples.

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

server/src/atlas/mod.rs

@@ -3,6 +3,7 @@
 //! These loaders are used by the runtime-background tier (D-200, D-206) when
 //! populating BodyWorldState (D-203). They are never called on the main tick thread.
 
+pub mod atlas_data_proxy;
 pub mod attractor_matching;
 pub mod believability;
 pub mod block_irregularity;