feat(simulation): dispatch RegionProfile layer in production (T-1032)

The D-239 carrier layer (T-1023/1024/1026) only ran in tests because every
production AnalyzeBody enqueue passed body_params: None. Wire the real path:

- New BodyParamsReader (server/src/atlas/body_params_reader.rs): read-only
  systems.db reader, joins bodies -> star_systems (LEFT JOIN) for the climate/
  tectonic inputs. SQL verified against systems-schema.sql. All fields Option,
  NULLs handled; tectonic_activity absent from schema -> None (derives from
  planet_class). 5 unit tests.
- layer_proxy.rs: on cache miss, read the body's params and pass
  Some(Box::new(..)). On read error, warn + fall back to None (cascade stops at
  Settlement, no panic) — graceful degradation.
- plugin.rs / main.rs: register BodyParamsReaderResource (CityContextReader
  pattern) and thread it through serve_atlas_requests.

BodyWorldState.regions now populates for real bodies in the D-206 background
pass. End-to-end tests cover wired (regions populated) + unwired (empty) paths.

cargo test 1504 pass, clippy -D warnings clean, fmt clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server/src/main.rs

@@ -215,6 +215,24 @@ fn main() {
         ),
     }
 
+    // Body physical params reader for RegionProfile carrier layer (T-1032, D-239 §1):
+    // reads hydrosphere / atmosphere / planet_class / orbital_period_days /
+    // axial_tilt_deg / spectral_class / star_type on a cache miss so the Rayon
+    // cascade work item stays DB-free (D-225 pattern).
+    match settled_reach_server::atlas::body_params_reader::BodyParamsReader::open(&systems_db_path)
+    {
+        Ok(reader) => {
+            tracing::info!("Body params reader opened: {:?}", systems_db_path);
+            app.insert_resource(
+                settled_reach_server::atlas::body_params_reader::BodyParamsReaderResource(reader),
+            );
+        }
+        Err(e) => tracing::warn!(
+            "Body params reader unavailable ({}). RegionProfile layer will be skipped.",
+            e
+        ),
+    }
+
     // Initialize SQLite settings store (#627).
     // Path: alongside save files in the server's working directory.
     let settings_path = std::path::PathBuf::from("settings.db");