feat: world-grid level materials + real movement test suite

- Generated CC0-style prototype grid textures (0.5 m cells) and a shared
  LevelMaterials factory: world-space triplanar mapping over every code-built
  level (test level, dust2, procedural arena) with the existing color coding
  kept as tints. Readable surfaces at speed instead of flat color boxes;
  materials are cached per tint so identical surfaces batch.
- .gdignore + .gitignore the raw downloaded asset packs in addons/ whose
  overlong paths broke Godot import scans and spammed git warnings.
- Replaced the rotted FSM test file (invalid call(t) on Callables, stateless
  stub nodes, hung forever without quitting) with a real suite: 10 tests
  covering state registration, jump bookkeeping, wall-run momentum
  preservation and upward-carry cap, per-player dash cooldown (regression for
  the old shared static), dash speed stacking, chain soft cap, landing
  events, and slide entry momentum. New headless entrypoint:
  godot --headless --path . -s res://movement/tests/run_fsm_tests.gd

Co-Authored-By: Claude Fable 5 <[email protected]>

scenes/maps/level_materials.gd

@@ -0,0 +1,41 @@
+extends Object
+class_name LevelMaterials
+
+## Shared prototype-grid materials for code-built levels.
+##
+## Every level builder makes its geometry from flat-colored boxes; this gives
+## them all the same world-space grid surface (0.5 m cells via triplanar
+## mapping) so speed and distance stay readable at movement-shooter velocity,
+## while keeping each builder's color coding as a tint.
+
+const GRID_GRAY := "res://assets/textures/prototype/grid_gray.png"
+const GRID_DARK := "res://assets/textures/prototype/grid_dark.png"
+
+## One texture tile = 2 m of world, so one grid cell = 0.5 m.
+const WORLD_UNITS_PER_TILE := 2.0
+
+static var _cache: Dictionary = {}
+
+
+## A tinted grid material. Cached per (tint, dark) so identical surfaces share
+## one material (fewer draw-state changes, and edits apply everywhere).
+static func tinted(tint: Color, dark: bool = false) -> StandardMaterial3D:
+	var key := "%s|%s" % [tint.to_html(), dark]
+	if _cache.has(key):
+		return _cache[key]
+	var mat := StandardMaterial3D.new()
+	var tex_path := GRID_DARK if dark else GRID_GRAY
+	var tex: Texture2D = load(tex_path) if ResourceLoader.exists(tex_path) else null
+	if tex:
+		mat.albedo_texture = tex
+		# World triplanar: boxes need no UVs and the grid stays world-scaled.
+		mat.uv1_triplanar = true
+		mat.uv1_world_triplanar = true
+		mat.uv1_scale = Vector3.ONE / WORLD_UNITS_PER_TILE
+	# The texture is grayscale ~mid value; multiply by ~2x-brightened tint to
+	# land near the original flat color while keeping the grid contrast.
+	mat.albedo_color = Color(
+		minf(tint.r * 1.9, 1.0), minf(tint.g * 1.9, 1.0), minf(tint.b * 1.9, 1.0))
+	mat.roughness = 0.85
+	_cache[key] = mat
+	return mat