feat(simulation): D-232 three-phase trait draw + deviation/swerve system (T-994, T-1003)

T-994 — three-phase draw replacing the flat splitmix64 flavor pick:
- Phase 1 body K-draw (trait_draw.rs): hard gates -> soft weights (two-part
  geographic_sector join, PR #148) -> SeedChain::for_body-seeded weighted
  draw of K (5/3/1/0 by ComplexityTier), pins count toward K, coverage-aware
  over a new body-level district-type-mix aggregate threaded into
  CityGenerationContext at L3->L4 dispatch.
- Phase 2 district-dominant pick keyed by the D-243 2048m District cell —
  settlements sharing a cell independently derive the identical template.
  Resolved at dispatch, never in FillChunk (T-987 stays pure).
- trait_catalog_reader.rs: systems.db reader for trait_templates +
  atlas_body_trait_bias (D-225 resource pattern), registered in main.rs
  with graceful degradation.
- BlockSkeleton carries district_type; assign_block_tags is a pure lookup.

T-1003 — deviation/swerve system (trait_swerve.rs):
- ArchitectureFlavorRef is now InVocabulary(u8) | Swerve(tag).
- Rare per-building wildcard: foreign-import pool (other corridors +
  cross_corridor) driven by Epicenter/Passage tier, mixed faction,
  road-graph degree; heritage-callback pool (own-corridor heritage) driven
  by isolation, remote tier, founding_age_years. Integer bps, base 100,
  cap 300 per driver — placeholder constants pending calibration.
- Sparsity escape hatch = same mechanism, necessity-triggered at the
  phase-2 pick (deterministic max-weight over the hard-gate-eligible pool).
- New SeedDomains: TraitVocabulary(13) / TraitDistrict(14) / TraitSwerve(15).

Governance: D-232 amended (district pinned to the D-243 2048m tier — the
D-222/D-243 redefinition was never captured; swerve driver mappings +
placeholder rates recorded), D-229 flavor_ref field updated to the enum
shape, D-235 amended (T-995 vocabulary ratification note; rides here due
to single-file entanglement).

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

server/src/main.rs

@@ -234,6 +234,28 @@ fn main() {
         ),
     }
 
+    // D-232 trait-template catalog reader (T-994): reads `trait_templates` +
+    // `atlas_body_trait_bias` on a body-analysis completion so the L3→L4 dispatch
+    // aggregation (atlas::plugin::drain_generation_completions) can run the
+    // three-phase draw. Absent → trait_selection stays empty for every body
+    // (the pre-T-994 degenerate behaviour), not a hard failure.
+    match settled_reach_server::atlas::trait_catalog_reader::TraitCatalogReader::open(
+        &systems_db_path,
+    ) {
+        Ok(reader) => {
+            tracing::info!("Trait catalog reader opened: {:?}", systems_db_path);
+            app.insert_resource(
+                settled_reach_server::atlas::trait_catalog_reader::TraitCatalogReaderResource(
+                    reader,
+                ),
+            );
+        }
+        Err(e) => tracing::warn!(
+            "Trait catalog reader unavailable ({}). Architecture-flavor draw will stay empty.",
+            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");