Drop a dead initial value in PlayableBoundsRule, guard
DiveSite.configure() when called before the node is in the tree, and
align the zone 1 brief with what was built: generic dive_site.tscn,
the resolved collision check, and the graybox shader deviation.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
DiveSite.configure() builds the height field once (TerrainHeightField
validates the data) instead of running the definition validation and
then the field construction again; the composition root relies on the
error returned by configure(). The collision shape takes the field's
row-major elevations directly instead of copying 263k cells one by one.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>