feat(tooling): generate_atlas.py city + infrastructure pipeline and atlas DB index (#832)

Implements the Phase 3 atlas content generator per D-191 §3, §8, and §9.

Pipeline per body (terrain-aware, deterministic per seed + body):
  1. Simulate terrain via planet_simulation.simulate().
  2. Analyse continents (flood-fill), habitability (temp/moisture/slope +
     coastal bonus), river mouths, and a terrain A* cost grid.
  3. Place cities sequentially — capital first (habitability + river-mouth
     bias), then corridor growth via multi-source Dijkstra, quadrant-spread
     penalty after 2 cities in a quadrant, port-on-new-continent bonus at
     cities 3–4. ±25% noise for seed variation.
  4. Generate roads and railroads as an MST over city positions, with
     A* paths on the terrain cost grid (rail follows roads where possible).
  5. Place a transit POI at the capital (15% chance to scatter to a
     secondary city).

Output (canonical markers.json schema, pixel space per D-191 §8):
  - cities:    {id, name, kind, center:[r,c], population}
  - roads:     {id, name, kind, path:[[r,c],...]}
  - railroads: {id, name, kind, path:[[r,c],...]}
  - pois:      {id, name, kind, center:[r,c]}
  - existing rivers/oceans/mountain_ranges preserved untouched.

City names are left empty for gemma_naming.py (#833). Body population is
split across cities with geometric decay (capital ~50%, each subsequent
city half the previous). The 6 hand-authored bodies (Lendel, Edict,
Vuurkloof, Røros, Cairnside, Estrade) are detected by existing
`cities` and skipped for regeneration; their markers are still synced
to the DB index below.

Atlas index in systems.db (new):
  - atlas_body_grids, atlas_cities, atlas_roads, atlas_railroads,
    atlas_pois, atlas_rivers, atlas_oceans, atlas_mountain_ranges
  - Scalar metadata mirror of every markers.json — the implant atlas app
    and development queries can lookup cities/POIs/features without
    scanning 267 JSON files. Polyline geometry stays in the markers.json
    files next to the heightmaps (used by the renderer); the DB only
    stores filterable scalar fields plus `point_count` as a length proxy.
  - Schema lives in server/data/systems-schema.sql; generate_atlas.py
    mirrors the CREATE TABLE IF NOT EXISTS block so it runs against any
    DB state (matches the economy-db importer pattern).
  - Populated and refreshed on every run. Each body's rows are deleted
    and reinserted deterministically — no stale state.

Also fixes a pre-existing WIP bug in the quadrant-saturation penalty
loop (a stray outer `for r in range(GRID_H)` with unreachable breaks
meant only the NW quadrant was ever checked).

Runtime: 280s for all 267 inhabited bodies on a single core. 265 bodies
updated this run, 6 hand-authored bodies synced to DB without
regeneration.

Atlas index after run:
  atlas_cities             329    (15 hand-authored + 314 awaiting #833)
  atlas_roads               46
  atlas_railroads           44
  atlas_pois               287
  atlas_rivers            2034
  atlas_oceans             696
  atlas_mountain_ranges   1953
  atlas_body_grids         267

server/data/systems-schema.sql

@@ -330,6 +330,99 @@ CREATE TABLE IF NOT EXISTS corp_lifecycle_events (
     created_at TEXT DEFAULT (datetime('now'))
 );
 
+-- Atlas index (D-191 §8, #832) — scalar metadata mirror of markers.json files.
+-- Source of truth is wiki/star-systems/.../markers.json (next to the heightmap);
+-- these tables exist so the atlas implant app and development queries don't
+-- have to scan hundreds of JSON files. Polyline geometry stays in the files —
+-- the DB only stores scalar/filterable fields + `point_count` as a rough length
+-- proxy. Populated and refreshed by tooling/planet-gen/generate_atlas.py.
+
+-- Per-body grid dimensions (one row per body that has a markers.json).
+-- Lets any query interpret the pixel coordinates below without touching disk.
+CREATE TABLE IF NOT EXISTS atlas_body_grids (
+    body_id TEXT PRIMARY KEY REFERENCES bodies(body_id),
+    grid_w INTEGER NOT NULL,
+    grid_h INTEGER NOT NULL,
+    updated_at TEXT DEFAULT (datetime('now'))
+);
+
+CREATE TABLE IF NOT EXISTS atlas_cities (
+    city_id TEXT PRIMARY KEY,                   -- "<body_id>/<local_id>" e.g. "GJ380c/city_0"
+    body_id TEXT NOT NULL REFERENCES bodies(body_id),
+    local_id TEXT NOT NULL,                     -- "city_0", "city_1" — matches markers.json id
+    name TEXT NOT NULL DEFAULT '',
+    kind TEXT NOT NULL,                         -- capital|city
+    center_row INTEGER NOT NULL,
+    center_col INTEGER NOT NULL,
+    population INTEGER NOT NULL DEFAULT 0,
+    updated_at TEXT DEFAULT (datetime('now'))
+);
+
+CREATE TABLE IF NOT EXISTS atlas_roads (
+    road_id TEXT PRIMARY KEY,                   -- "<body_id>/<local_id>"
+    body_id TEXT NOT NULL REFERENCES bodies(body_id),
+    local_id TEXT NOT NULL,
+    name TEXT NOT NULL DEFAULT '',
+    kind TEXT NOT NULL,                         -- commercial|highway|rural|...
+    point_count INTEGER NOT NULL,               -- path length proxy (full geometry in markers.json)
+    updated_at TEXT DEFAULT (datetime('now'))
+);
+
+CREATE TABLE IF NOT EXISTS atlas_railroads (
+    railroad_id TEXT PRIMARY KEY,               -- "<body_id>/<local_id>"
+    body_id TEXT NOT NULL REFERENCES bodies(body_id),
+    local_id TEXT NOT NULL,
+    name TEXT NOT NULL DEFAULT '',
+    kind TEXT NOT NULL,                         -- passenger_freight|freight|maglev|...
+    point_count INTEGER NOT NULL,
+    updated_at TEXT DEFAULT (datetime('now'))
+);
+
+CREATE TABLE IF NOT EXISTS atlas_pois (
+    poi_id TEXT PRIMARY KEY,                    -- "<body_id>/<local_id>"
+    body_id TEXT NOT NULL REFERENCES bodies(body_id),
+    local_id TEXT NOT NULL,
+    name TEXT NOT NULL DEFAULT '',
+    kind TEXT NOT NULL,                         -- transit|institutional|cultural|...
+    center_row INTEGER NOT NULL,
+    center_col INTEGER NOT NULL,
+    updated_at TEXT DEFAULT (datetime('now'))
+);
+
+CREATE TABLE IF NOT EXISTS atlas_rivers (
+    river_id TEXT PRIMARY KEY,                  -- "<body_id>/<local_id>"
+    body_id TEXT NOT NULL REFERENCES bodies(body_id),
+    local_id TEXT NOT NULL,
+    name TEXT NOT NULL DEFAULT '',              -- empty for untitled procedural rivers
+    point_count INTEGER NOT NULL,
+    updated_at TEXT DEFAULT (datetime('now'))
+);
+
+CREATE TABLE IF NOT EXISTS atlas_oceans (
+    water_id TEXT PRIMARY KEY,                  -- "<body_id>/<local_id>"
+    body_id TEXT NOT NULL REFERENCES bodies(body_id),
+    local_id TEXT NOT NULL,
+    name TEXT NOT NULL DEFAULT '',
+    kind TEXT NOT NULL,                         -- lake|sea|ocean
+    center_row INTEGER NOT NULL,
+    center_col INTEGER NOT NULL,
+    area_fraction REAL NOT NULL DEFAULT 0.0,    -- fraction of heightmap area covered
+    updated_at TEXT DEFAULT (datetime('now'))
+);
+
+CREATE TABLE IF NOT EXISTS atlas_mountain_ranges (
+    range_id TEXT PRIMARY KEY,                  -- "<body_id>/<local_id>"
+    body_id TEXT NOT NULL REFERENCES bodies(body_id),
+    local_id TEXT NOT NULL,
+    name TEXT NOT NULL DEFAULT '',
+    center_row INTEGER NOT NULL,
+    center_col INTEGER NOT NULL,
+    peak_row INTEGER NOT NULL,
+    peak_col INTEGER NOT NULL,
+    area_cells INTEGER NOT NULL DEFAULT 0,
+    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);
@@ -364,3 +457,15 @@ CREATE INDEX IF NOT EXISTS idx_brand_products_origin ON brand_products(origin_sy
 CREATE INDEX IF NOT EXISTS idx_brand_products_tier ON brand_products(brand_tier);
 CREATE INDEX IF NOT EXISTS idx_brand_inputs_commodity ON brand_inputs(commodity_id);
 CREATE INDEX IF NOT EXISTS idx_corp_lifecycle_events_corp ON corp_lifecycle_events(corp_id);
+-- Atlas index (D-191 §8, #832)
+CREATE INDEX IF NOT EXISTS idx_atlas_cities_body ON atlas_cities(body_id);
+CREATE INDEX IF NOT EXISTS idx_atlas_cities_kind ON atlas_cities(kind);
+CREATE INDEX IF NOT EXISTS idx_atlas_cities_population ON atlas_cities(population);
+CREATE INDEX IF NOT EXISTS idx_atlas_cities_name ON atlas_cities(name);
+CREATE INDEX IF NOT EXISTS idx_atlas_roads_body ON atlas_roads(body_id);
+CREATE INDEX IF NOT EXISTS idx_atlas_railroads_body ON atlas_railroads(body_id);
+CREATE INDEX IF NOT EXISTS idx_atlas_pois_body ON atlas_pois(body_id);
+CREATE INDEX IF NOT EXISTS idx_atlas_pois_kind ON atlas_pois(kind);
+CREATE INDEX IF NOT EXISTS idx_atlas_rivers_body ON atlas_rivers(body_id);
+CREATE INDEX IF NOT EXISTS idx_atlas_oceans_body ON atlas_oceans(body_id);
+CREATE INDEX IF NOT EXISTS idx_atlas_mountain_ranges_body ON atlas_mountain_ranges(body_id);