feat(mapgen): add generator registry

src/gen/init.lua

@@ -0,0 +1,32 @@
+-- Registry of selectable dungeon generators. Every entry takes the same
+-- (width, height, rng, options) signature and returns a carved Map. After
+-- generation connectivity is enforced so the dungeon layer can rely on a single
+-- reachable region regardless of which algorithm ran.
+
+local Connect = require("gen.connect")
+
+local Gen = {}
+
+Gen.generators = {
+  rooms = require("gen.rooms").generate,
+  bsp = require("gen.bsp").generate,
+  cellular = require("gen.cellular").generate,
+  drunkard = require("gen.drunkard").generate,
+}
+
+-- Deterministic ordering of names for callers that want to cycle generators by
+-- depth without depending on hash iteration order.
+Gen.order = { "rooms", "bsp", "cellular", "drunkard" }
+
+function Gen.has(name)
+  return Gen.generators[name] ~= nil
+end
+
+function Gen.build(name, width, height, rng, options)
+  local generate = Gen.generators[name]
+  local map = generate(width, height, rng, options)
+  local reachable = Connect.ensure(map, rng)
+  return map, reachable
+end
+
+return Gen