Adds a [layer_names] section to project.godot (Ships/Ball/Arena/
GoalSensor) and sets collision_layer/collision_mask on the 4 physics
body roots (Ship, Ball, Goal Area3D, ArenaBoundary StaticBody3D),
which previously all sat on the default layer 1 / mask 1 so every
body broadphase-tested against every other.
Ships collide with ships/ball/arena but no longer test against the
goal sensor; the goal's mask (Ball only) is the physics-level fix for
what goal.gd's is_in_group("ball") check was doing defensively in
code (left in place, now a no-op guard). ArenaBoundary's runtime-
generated CollisionShape3D children inherit layer/mask from the
StaticBody3D root automatically.
Verified live via godot-mcp under Jolt Physics: ship-vs-ship and
ship-vs-ball collisions still transfer momentum, the ball still
bounces off arena walls, a ball entering a goal still fires
goal_scored (score updates / HUD reset), and a ship teleported into a
goal recess produces zero overlapping bodies on the goal Area3D (was
reachable before, physics-level fix confirmed, not just the code
guard). Headless smoke test (free_play.tscn) is clean.
Ship gets a greebled hull, tapered nose, swept canopy, twin engine nacelles,
and tail fin (built via the vendored Blender MCP, generator committed at
tools/blender/gen_ship.py) in place of the 5 flat primitives. The ball is
fully remodeled as a smooth round sphere with a crossed emissive accent
pattern (gen_ball.py), replacing the old flat-shaded gold_ball rather than
just tweaking its material.
Node names (Nose/TailFin) are preserved for Ship._apply_team_color(), and
the RigidBody3D/CollisionShape3D physics on both ship.tscn and ball.tscn are
untouched so RL-trained bots and flight feel stay valid. Each part's mesh is
extracted to a standalone .res (tools/blender/extract_meshes.gd) rather than
referenced via glb::ArrayMesh_xxx sub-paths, which don't reliably resolve
across scene files and were silently rendering both models invisible.