feat(schema): add bodies and stations tables to systems.db

New tables for the celestial body hierarchy below system level:
- bodies: planets, moons, gas giants, asteroid belts, oort clouds
  with physical properties, settlement data, and cultural overrides
- stations: orbital/surface facilities with type, population,
  docking class, and gate infrastructure flag

Naming convention: GJ-{n}b (planet), GJ-{n}b-1 (moon),
GJ-{n}b-S1 (station), GJ-{n}-oort (oort cloud).
Self-referential parent_body_id for moon→planet relationships.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/data/systems-schema.sql

@@ -121,6 +121,72 @@ CREATE TABLE IF NOT EXISTS system_culture (
 -- narrative_hook, calibration_note) lives in wiki markdown files only.
 -- No DB mirror — read the file if you need the text.
 
+-- Celestial bodies — planets, moons, gas giants, asteroid belts, oort clouds
+-- Naming convention:
+--   GJ-{n}b/c/d...    — planets (innermost first)
+--   GJ-{n}Ab/c/d...   — planets orbiting primary (binary systems)
+--   GJ-{n}d-1          — first moon of third planet
+--   GJ-{n}-oort        — oort cloud region
+--   GJ-{n}-belt        — asteroid belt
+CREATE TABLE IF NOT EXISTS bodies (
+    body_id TEXT PRIMARY KEY,
+    system_id TEXT NOT NULL REFERENCES star_systems(system_id),
+    parent_body_id TEXT REFERENCES bodies(body_id),  -- NULL for planets; parent planet for moons
+
+    -- Classification
+    body_type TEXT NOT NULL,            -- planet, moon, gas_giant, asteroid_belt, oort_cloud
+    orbit_index INTEGER,               -- innermost = 1 (planets around star, moons around planet)
+    proper_name TEXT,                   -- "Xin Chengdu", NULL for unnamed
+
+    -- Physical
+    mass_class TEXT,                    -- terrestrial, super_earth, ice_giant, gas_giant, dwarf
+    atmosphere TEXT,                    -- breathable, thin, toxic, none, dense
+    surface_gravity REAL,              -- in g (Earth = 1.0), NULL for gas giants
+    biome_summary TEXT,                -- temperate, arid, frozen, oceanic, volcanic, barren, mixed
+    hydrosphere TEXT,                  -- ocean, ice, rivers, none, subsurface
+
+    -- Settlement
+    inhabited INTEGER NOT NULL DEFAULT 0,
+    population INTEGER DEFAULT 0,
+    economic_role TEXT,                -- manufacturing, agricultural, extraction, research, transit
+    founding_age_years INTEGER,
+    settlement_pattern TEXT,           -- urban_concentrated, dispersed_rural, orbital_only, domed, cave
+
+    -- Cultural (inherited from system, can override)
+    cultural_corridor TEXT,            -- override system corridor if different
+    industrial_corridor TEXT,          -- MVG, Gate_Corp, DSMC, Prometheus, Agricultural_Syndic
+
+    -- Rendering
+    terrain_reference TEXT,            -- heightmap path when authored, NULL otherwise
+    screenshot_path TEXT,              -- planetary shader screenshot path
+
+    updated_at TEXT DEFAULT (datetime('now'))
+);
+
+-- Stations and orbital facilities
+-- Naming: GJ-{n}b-S1 (first station orbiting planet b), GJ-{n}-oort-S1 (horizon station)
+CREATE TABLE IF NOT EXISTS stations (
+    station_id TEXT PRIMARY KEY,
+    system_id TEXT NOT NULL REFERENCES star_systems(system_id),
+    orbits_body_id TEXT REFERENCES bodies(body_id),
+
+    -- Classification
+    station_type TEXT NOT NULL,         -- horizon, commercial, military, research, industrial, agricultural, transit
+    proper_name TEXT,                   -- "Chengdu Orbital", "Horizon Station"
+
+    -- Settlement
+    population INTEGER DEFAULT 0,
+    economic_role TEXT,
+    governance_type TEXT,              -- can differ from system governance
+
+    -- Infrastructure
+    docking_class TEXT,                -- major, standard, restricted, none
+    has_gate_infrastructure INTEGER DEFAULT 0,
+    district_count INTEGER DEFAULT 1,
+
+    updated_at TEXT DEFAULT (datetime('now'))
+);
+
 -- Indexes
 -- astronomical_id removed: system_id IS the GJ catalog number
 CREATE INDEX IF NOT EXISTS idx_star_systems_sector ON star_systems(geographic_sector);
@@ -132,3 +198,10 @@ CREATE INDEX IF NOT EXISTS idx_historical_events_system ON historical_events(sys
 CREATE INDEX IF NOT EXISTS idx_system_factions_dominant ON system_factions(dominant_faction);
 CREATE INDEX IF NOT EXISTS idx_system_economy_tier ON system_economy(economic_tier);
 CREATE INDEX IF NOT EXISTS idx_system_culture_archetype ON system_culture(primary_archetype);
+CREATE INDEX IF NOT EXISTS idx_bodies_system ON bodies(system_id);
+CREATE INDEX IF NOT EXISTS idx_bodies_parent ON bodies(parent_body_id);
+CREATE INDEX IF NOT EXISTS idx_bodies_type ON bodies(body_type);
+CREATE INDEX IF NOT EXISTS idx_bodies_inhabited ON bodies(inhabited);
+CREATE INDEX IF NOT EXISTS idx_stations_system ON stations(system_id);
+CREATE INDEX IF NOT EXISTS idx_stations_orbits ON stations(orbits_body_id);
+CREATE INDEX IF NOT EXISTS idx_stations_type ON stations(station_type);