M1/M2: chase camera + expressway map v2

CameraController (client):
- Scriptable chase cam only while in the DriveSeat; restores default on exit
- Frame-rate independent damped follow with look-ahead aim point
- Flat horizon (ignores car pitch/roll) so bumps don't shake the view
- Speed-based FOV kick (quadratic ramp) for sense of pace
- Cleans up on Died/despawn

MapBuilder v2:
- Highway extended 2400 -> 3200 studs with distinct feature zones
- Gantry arches (seg 2), enclosed neon-lit tunnel (seg 3), jump ramp +
  landing pair on the right lane (seg 4, left lane stays flat)
- Procedural neon skyline towers flanking both sides (deterministic seed,
  same city every server)
- End kill-wall so you can't sail off the far edge

docs/ROADMAP.md

@@ -21,14 +21,19 @@ to owner + son. Cars persist between sessions. CI green on a self-hosted runner.
       (driver owns network physics). **Needs a Studio playtest to tune feel.**
 - [ ] Import the **real RX-7 mesh**; weld the shell onto the chassis `Body`.
       See `docs/MESH_SWAP.md` for the exact steps (needs Studio for asset upload).
-- [ ] Tune acceleration curve, grip, and the chase camera (after first playtest).
+- [ ] Tune acceleration curve and grip (after first playtest).
+- [x] **Chase camera**: scriptable follow cam while seated — damped chase with
+      look-ahead, flat horizon (ignores car pitch/roll), speed-based FOV kick.
+      `src/client/CameraController.luau`. Tune constants after playtest.
 - [ ] Sound: engine loop, tire screech, boost.
 **Exit test:** the RX-7 is genuinely fun to just drive around. Ship nothing else
 until this is true.
 
 ## M2 — More cars + polish (still no racing)
 - [ ] Import a few more real car meshes.
-- [ ] Better map: more expressway sections, ramps, tunnels, scenery.
+- [x] Better map v2: 3200-stud expressway with gantry arches, a neon-lit
+      tunnel, jump ramps (right lane; left stays flat), end wall, and a
+      procedural neon skyline flanking the route.
 - [ ] Day/night, weather mood.
 
 ## M3 — Racing (the first "game" layer)