Wildlife and nature: animals, beehives, bushes, flowers, rocks, logs

New stdlib module wildlife.rhai:
- Animals (new palette category): Deer (stag with antlers, does, fawns),
  Wild boar, Fox, Elephant (bull with tusks, cow, calf), Rabbits. Low-poly
  solids from faces (loft, tube), parts drawn back to front by depth, faces
  edged in their own shade (class beast). Herds scatter round a spot, each
  animal its own sprite facing about the object's rotation. Grazing
  animals switch between two head poses (iso-pose2 groups), elephants curl
  their trunks, rabbits hop.
- Birds and Butterflies as flocks: swim() takes a shape (bird, fly, bee);
  wings flap out of step. Fish output unchanged.
- Beehives on stands with supers, lids, entrances and bees flying round;
  Bush (round, flowering, berries); Flowers (bed in rows or meadow); Rocks;
  Log or stump. g-meadow and g-soil ground materials.
- polyline() takes 3D points as documented (antlers).

Theme colours for dark and light, viewer CSS for poses, flapping, hopping.
examples/country: elephants in a paddock with a cut corner, deer at a
forest edge, boar, fox, rabbits, an apiary by a meadow, a pond, a lane,
fence and hedgerow at angles; Country demo in the web Studio and deploy.
MCP guidance, README, SCRIPTING, ROADMAP.

Tests: Rust 78, Studio 122; existing examples draw the same (only the
embedded theme CSS grew).

README.md

@@ -79,6 +79,17 @@ The **House** palette has the parts, **Furniture** the interior:
 swimming round under lily pads, ripples and reeds; trees, hedges and rows of
 trees are in Nature.
 
+**Animals and nature**: Deer (a herd of a stag, does and fawns, or one
+kind), Wild boar, Fox, Elephant (bull, cow, calf), Rabbits, a flock of Birds
+circling and Butterflies; Beehives on stands with bees flying round, Bushes
+(round, flowering, berries), Flowers (a bed in rows or a wildflower meadow),
+Rocks and a Log or stump. Animals are low-poly solids that read from every
+side; a herd scatters about the object's spot, each animal its own sprite.
+Grazing animals lower and raise their heads in turn, elephants curl their
+trunks, rabbits hop, birds flap. `examples/country` (Country demo in the web
+Studio) puts them in a countryside corner with a lane, fence and hedgerow at
+an angle.
+
 **Fences and walls** around the plot: the Fence has six designs (mesh, wooden
 boards, steel bars, mesh on a stone base, cobble wall, brick wall with
 pillars). Fences and site walls whose ends meet join like house walls: corners