Patch MapPosition and BoundingBox to the named form

The api documents both as a union with a positional array because both
are accepted as input, which makes every read of `.x` or `.left_top`
optional. Everything read back from the game uses the named form, so
the positional variant is removed and we now always write it that way
too.

The spawn area config offsets and the mine depletion search areas were
the only positional writes left, and apply_offset no longer needs its
fallback.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

type.patch.lua

@@ -0,0 +1,8 @@
+---@meta
+
+--- The api documents MapPosition and BoundingBox as a union of the named form
+--- and a positional array, because both are accepted as input. Everything read
+--- back from the game uses the named form, and we always write it that way too,
+--- so the positional variant is removed here.
+---@alias MapPosition MapPosition.struct
+---@alias BoundingBox BoundingBox.struct