feat(db): body_radius_km scatter + gas giant/moon scale classes

Deterministic ±scatter on body radii seeded by body_id hash — no two
bodies share the same radius. Gas giants 40k-60k km, moons 200-2600 km,
rocky planets ±15% from class base. Oort/asteroid skip radius (NULL).
Sol system gets real planetary radii. body_radius_km exported to
star_map_data.json for client orbital diagram sizing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tooling/generate-star-map-data.py

@@ -197,7 +197,7 @@ def generate() -> dict:
         cur.execute("""
             SELECT system_id, body_id, parent_body_id, orbit_index, body_type,
                    proper_name, atmosphere, inhabited, population,
-                   terrain_reference, mass_class
+                   terrain_reference, mass_class, body_radius_km
             FROM bodies
             ORDER BY system_id, orbit_index
         """)
@@ -215,6 +215,7 @@ def generate() -> dict:
                 "population": int(row["population"] or 0),
                 "terrain_reference": row["terrain_reference"],
                 "mass_class": row["mass_class"],
+                "body_radius_km": float(row["body_radius_km"] or 0),
             })
 
         # Per-system station list for atlas orbital diagram (D-191 §6)