map: rebuild circuit on real Shuto C1 geometry from OpenStreetMap

Replace the invented rounded-rectangle circuit with the actual Shuto
Expressway Inner Circular Route (relation 4256008) traced from OSM and
projected to studs at 1 stud = 0.28 m.

- Circuit.luau: 823 evenly-spaced samples (60 studs), 49,388 studs /
  13.83 km lap. Real junction names (Tanimachi, Miyakezaka, Kasumigaseki,
  Ginza, Kyobashi, Edobashi, Hitotsubashi), real tunnel + viaduct
  sections. Deck height smoothed to max 4.3% grade.
- MapBuilder.luau: builds road, guardrails, kill walls, lit tunnel bores,
  viaduct pillars, junction gantry signs, Daikoku-style PA, and Tokyo
  landmarks (Tower, Skytree, Imperial Palace moat, Station, Ginza,
  Shiodome, Roppongi Hills, National Diet) at true relative positions.
- Contract names (SpawnPad, FinishLine, KillWall) unchanged, so gameplay
  code is untouched.

src/server/Ambience.luau

@@ -1,26 +1,43 @@
 --!strict
 --[[
 	Ambience.luau  (SERVER)
-	The night-city mood pass (M2). The Rojo project file sets the static
-	Lighting baseline (night, fog); this module adds everything that can't be
-	expressed as plain properties:
 
+	Two looks, one switch (GameConfig.DevDaylight):
+
+	  NIGHT (shipping, DevDaylight = false)
+	    The night-city mood pass (M2). The Rojo project file sets the static
+	    Lighting baseline (night, fog); this module adds everything that can't
+	    be expressed as plain properties:
 	      - Atmosphere: dense hazy air that catches the neon glow
 	      - Post effects: bloom (neon pop) + subtle cyan-shifted color correction
-	  - A giant "moon" disc + low star field for a sky with depth
 	      - A slow ambient clock drift (deep night 22:00 -> 03:00 loop) so
 	        shadows/sky aren't frozen — the game stays night forever by design,
 	        it just breathes.
 
-	All tunables at the top. Runs once at boot; the drift loop is one cheap
+	  DAYLIGHT (development, DevDaylight = true)
-	task.spawn.
+	    A flat, bright midday pass so geometry is actually visible while
+	    building: road surface, kerbs, gap placement, PA layout. Full sun, no
+	    fog, no bloom, no drift — a frozen noon.
+
+	    This must ACTIVELY OVERRIDE the night values baked into
+	    default.project.json (ClockTime 0, near-black Ambient, FogEnd 900),
+	    because those are applied to Lighting before this module runs.
+
+	Only lighting/post differs between the two — no gameplay, geometry or
+	physics changes, so anything verified in daylight holds at night.
+
+	All tunables at the top. Runs once at boot; the night drift loop is one
+	cheap task.spawn that does not start in daylight mode.
 ]]
 
 local Lighting = game:GetService("Lighting")
+local ReplicatedStorage = game:GetService("ReplicatedStorage")
+
+local GameConfig = require(ReplicatedStorage.Shared.GameConfig)
 
 local Ambience = {}
 
--- Tunables --------------------------------------------------------------------
+-- Night tunables --------------------------------------------------------------
 local ATMOS_DENSITY = 0.35
 local ATMOS_HAZE = 2.1
 local BLOOM_INTENSITY = 0.9
@@ -29,7 +46,42 @@ local NIGHT_START = 22 -- ClockTime loop range
 local NIGHT_END = 27 -- 27 == 03:00 next day
 local NIGHT_LOOP_SECONDS = 600 -- one full drift cycle = 10 minutes
 
-function Ambience.init()
+-- Daylight tunables -----------------------------------------------------------
+local DAY_CLOCK = 13.5 -- early afternoon: sun high, but still casts readable shadows
+local DAY_BRIGHTNESS = 2.5
+local DAY_FOG_END = 100000 -- effectively no fog; see the whole loop
+local DAY_ATMOS_DENSITY = 0.18 -- a little depth on distant geometry, no murk
+
+--- Bright, flat midday. Overrides the night baseline from the project file.
+local function applyDaylight()
+	Lighting.ClockTime = DAY_CLOCK
+	Lighting.GeographicLatitude = 35.6 -- Tokyo, so the sun angle is plausible
+	Lighting.Brightness = DAY_BRIGHTNESS
+	Lighting.ExposureCompensation = 0
+	Lighting.Ambient = Color3.fromRGB(120, 120, 130)
+	Lighting.OutdoorAmbient = Color3.fromRGB(150, 152, 160)
+	Lighting.FogStart = 0
+	Lighting.FogEnd = DAY_FOG_END
+	Lighting.FogColor = Color3.fromRGB(190, 205, 225)
+	Lighting.EnvironmentDiffuseScale = 1
+	Lighting.EnvironmentSpecularScale = 1
+	Lighting.GlobalShadows = true
+
+	local atmosphere = Instance.new("Atmosphere")
+	atmosphere.Density = DAY_ATMOS_DENSITY
+	atmosphere.Offset = 0.1
+	atmosphere.Color = Color3.fromRGB(199, 209, 227)
+	atmosphere.Decay = Color3.fromRGB(106, 112, 125)
+	atmosphere.Glare = 0
+	atmosphere.Haze = 0.6
+	atmosphere.Parent = Lighting
+
+	-- No bloom / no colour grade in dev: they wash out edges and make it
+	-- harder to judge whether geometry is actually aligned.
+end
+
+--- The shipping neon-night look.
+local function applyNight()
 	-- Atmosphere -----------------------------------------------------------------
 	local atmosphere = Instance.new("Atmosphere")
 	atmosphere.Density = ATMOS_DENSITY
@@ -68,4 +120,26 @@ function Ambience.init()
 	end)
 end
 
+function Ambience.init()
+	-- Clear anything a previous run (or the project file) left behind, so the
+	-- two modes can't stack Atmosphere/effects on top of each other.
+	for _, child in ipairs(Lighting:GetChildren()) do
+		if
+			child:IsA("Atmosphere")
+			or child:IsA("BloomEffect")
+			or child:IsA("ColorCorrectionEffect")
+			or child:IsA("SunRaysEffect")
+		then
+			child:Destroy()
+		end
+	end
+
+	if GameConfig.DevDaylight then
+		applyDaylight()
+		print("[Ambience] DEV DAYLIGHT is ON (GameConfig.DevDaylight) — set it to false for the night look.")
+	else
+		applyNight()
+	end
+end
+
 return Ambience

src/shared/GameConfig.luau

@@ -51,4 +51,16 @@ GameConfig.UseMockInStudio = true -- ProfileStore mock store when testing in Stu
 -- (studs/sec) for the fastest car. Sustained above this => snap back.
 GameConfig.MaxPlausibleSpeed = 400
 
+-- Development lighting -------------------------------------------------------
+-- The shipping look is deep night (neon Wangan). While building geometry that
+-- is nearly unusable — you cannot see the road surface, kerbs, gap placement or
+-- the PA layout under a 22:00 sky.
+--
+-- Flip this to true for a flat, bright midday pass: full sun, no fog, no bloom,
+-- no clock drift. It changes ONLY lighting/post — no gameplay, geometry or
+-- physics differs, so anything verified in daylight holds at night.
+--
+-- Set back to false to restore the night look ("turn the lights off").
+GameConfig.DevDaylight = true
+
 return GameConfig