feat(simulation): D-239 three-carrier foundation (T-1023/1024/1026)

First foundation slice of the Atlas-to-tile derivation model (epic T-974),
building the carrier layer ahead of its T-1027+ consumers.

T-1026 — Anti-squaring domain warp (D-239 §4): stateless pure
fn(seed,body_id,pos)->(f64,f64), ±8m, f64 to the final voxel then as-i32
truncation for IEEE-754 cross-target determinism. New domain_warp.rs,
SeedDomain::DomainWarp; golden-vector + cross-thread tests. Position math
only — D-010 integer discipline preserved downstream. Marked dead_code
until the T-1028 VoxelColumn pipeline consumes it.

T-1023 — RegionProfile carrier (D-239 §1,§10): new RegionProfile +
TectonicClass/GlaciationGrade/PrecipitationClass enums + BodyParams; derived
per-region river_threshold replacing the global 200 for tile consumers.
regions: BTreeMap on BodyWorldState, populated via the cascade's new
RegionProfile layer (runs when body_params is Some, else falls back to
Settlement). D-010 integer discipline, BTree ordering.

T-1024 — District climate primitives (D-239 §2): nullable temperature_c +
moisture on RegionProfile, mean-annual scalar (no clock dep; dynamic branch
deferred to Q-105). Hybrid inputs — new bodies.axial_tilt_deg column imported
from planet-gen body-defs (populate_axial_tilt_deg, 2611 bodies), luminosity
and orbital distance derived at runtime; greenhouse + diurnal-swing tables in
source-canonical climate_constants.toml. D-239 implementation note added.

cargo test: 1498 passed, 0 failed. clippy clean (pre-existing
large_enum_variant only). make check-systems-db: stamp fresh.

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

tooling/economy-db/import_economics.py

@@ -480,6 +480,7 @@ COLUMN_MIGRATIONS = [
     ("corporations", "shadow_economy_access", "INTEGER DEFAULT 0"),
     ("brand_products", "price_tier", "TEXT"),
     ("bodies", "body_radius_km", "REAL"),  # D-204 — physical radius in km, nullable
+    ("bodies", "axial_tilt_deg", "REAL"),  # T-1024, D-239 §2 — axial tilt from body-def frontmatter
     ("meta", "schema_sha", "TEXT"),
     ("atlas_city_names", "settlement_class", "TEXT"),  # D-196 — NULL until placement (#37)
     ("system_economy", "economic_specialization", "TEXT"),  # D-237 — authored specialization layer
@@ -1279,6 +1280,121 @@ def populate_body_radius_km(conn: sqlite3.Connection, dry_run: bool) -> int:
     return len(updates)
 
 
+def populate_axial_tilt_deg(conn: sqlite3.Connection, dry_run: bool) -> int:
+    """Populate bodies.axial_tilt_deg from planet-gen body-def frontmatter (T-1024).
+
+    Reads wiki/star-systems/*/bodies/*/index.md YAML frontmatter and extracts
+    ``orbit.axial_tilt_deg``. Only updates rows where axial_tilt_deg IS NULL
+    (preserves any future authoritative column writes).
+
+    Source: body_definition_parser.py writes ``orbit.axial_tilt_deg`` into each
+    body's index.md during the planet-gen batch run. This function mirrors
+    ``populate_body_radius_km`` in structure.
+    """
+    import yaml  # stdlib-compatible subset via PyYAML if available, else manual parse
+
+    def _parse_frontmatter_yaml(text: str) -> dict:
+        """Extract YAML frontmatter block from a markdown file."""
+        lines = text.split("\n")
+        if not lines or lines[0].strip() != "---":
+            return {}
+        end_idx = None
+        for i, line in enumerate(lines[1:], 1):
+            if line.strip() == "---":
+                end_idx = i
+                break
+        if end_idx is None:
+            return {}
+        fm_text = "\n".join(lines[1:end_idx])
+        try:
+            result = yaml.safe_load(fm_text)
+            return result if isinstance(result, dict) else {}
+        except Exception:
+            return {}
+
+    # Check if yaml is available; if not, use manual extraction.
+    try:
+        import yaml as _yaml_check  # noqa: F401
+        has_yaml = True
+    except ImportError:
+        has_yaml = False
+
+    if not has_yaml:
+        # Fallback: manual extraction of axial_tilt_deg from YAML frontmatter.
+        # Scans for "  axial_tilt_deg: <value>" under an "orbit:" block.
+        def _parse_frontmatter_manual(text: str) -> dict:
+            lines = text.split("\n")
+            if not lines or lines[0].strip() != "---":
+                return {}
+            in_orbit = False
+            result: dict = {}
+            for line in lines[1:]:
+                if line.strip() == "---":
+                    break
+                stripped = line.strip()
+                if stripped == "orbit:":
+                    in_orbit = True
+                    continue
+                if in_orbit:
+                    # Detect leaving the orbit block (non-indented key).
+                    if line and not line.startswith(" ") and not line.startswith("\t"):
+                        in_orbit = False
+                    elif stripped.startswith("axial_tilt_deg:"):
+                        _, _, val = stripped.partition(":")
+                        try:
+                            result["axial_tilt_deg"] = float(val.strip())
+                        except ValueError:
+                            pass
+            return result
+
+        def _parse_frontmatter_yaml(text: str) -> dict:  # type: ignore[misc]
+            return _parse_frontmatter_manual(text)
+
+    # Find all body index.md files.
+    body_dir_pattern = WIKI_STAR_SYSTEMS / "*" / "bodies" / "*" / "index.md"
+    import glob as _glob
+    body_files = sorted(_glob.glob(str(body_dir_pattern)))
+
+    # Build body_id → axial_tilt_deg mapping from frontmatter.
+    tilt_map: dict[str, float] = {}
+    for fpath in body_files:
+        try:
+            text = Path(fpath).read_text(encoding="utf-8")
+        except OSError:
+            continue
+        fm = _parse_frontmatter_yaml(text)
+        if not isinstance(fm, dict):
+            continue
+        body_id = fm.get("id")
+        orbit = fm.get("orbit", {})
+        if isinstance(orbit, dict):
+            tilt = orbit.get("axial_tilt_deg")
+        else:
+            tilt = None
+        if body_id and tilt is not None:
+            try:
+                tilt_map[str(body_id)] = float(tilt)
+            except (TypeError, ValueError):
+                pass
+
+    # Get all bodies where axial_tilt_deg IS NULL and body_id is in tilt_map.
+    rows = conn.execute(
+        "SELECT body_id FROM bodies WHERE axial_tilt_deg IS NULL"
+    ).fetchall()
+
+    updates = []
+    for (body_id,) in rows:
+        if body_id in tilt_map:
+            updates.append((tilt_map[body_id], body_id))
+
+    if not dry_run and updates:
+        conn.executemany(
+            "UPDATE bodies SET axial_tilt_deg = ? WHERE body_id = ?", updates
+        )
+
+    return len(updates)
+
+
 # Atlas geometry index tables (D-191). These hold computed positions — city
 # centres, road/river/rail polylines, ocean/mountain extents. Under D-223 the
 # Python atlas geometry generator was retired (#951); the deterministic
@@ -2414,6 +2530,11 @@ def main():
         n_bias = populate_atlas_body_trait_bias(conn, args.dry_run)
         print(f"        {n_bias} body trait-bias rows")
 
+        # 16. axial_tilt_deg from body-def frontmatter (T-1024, D-239 §2)
+        print("  [16/16] Populating axial_tilt_deg from body-def frontmatter...")
+        n_tilt = populate_axial_tilt_deg(conn, args.dry_run)
+        print(f"        {n_tilt} bodies updated with axial_tilt_deg")
+
         # Validate structural integrity (FK, chain refs, chain completeness).
         # These errors indicate broken imported data — do NOT commit.
         print("\n  Validating structural integrity...")