Initial MVP: drivable RX-7 vertical slice + server-authoritative systems

- Rojo + Wally project; ProfileStore (loleris) for safe saves
- Shared: GameConfig, Cars (RX-7 free starter), ProfileTemplate, Remotes
- Server: DataManager, Economy, CarManager, RaceManager, MapBuilder, AntiCheat
- Client: neon HUD + Garage/Dealership UI (buy/equip/upgrade), race/daily
- Procedural Tokyo expressway (spawn pad, finish line, neon pylons, kill walls)
- CI workflow (Gitea/GitHub), Makefile, selene+stylua clean, rojo builds
- Docs: README, GDD, realistic solo ROADMAP

docs/ROADMAP.md

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+# Roadmap — realistic solo-dev plan
+
+This replaces the original doc's optimistic 12-week timeline. It assumes **one
+part-time developer learning as they go**. Ship the vertical slice, then layer
+polish. Each milestone is independently playable/testable.
+
+> Rule of thumb: the original guide's "weeks" are really "milestones." Expect
+> **4–8 months** of part-time work to a polished, launch-ready MVP. That's normal.
+> The goal of this order is that you always have something that *runs*.
+
+---
+
+## ✅ M0 — Vertical slice (DONE — this repo)
+Drive → race → earn → buy/upgrade → **save**. Server-authoritative. Placeholder
+RX-7 block car, procedural expressway. Proves the whole stack end to end.
+
+## M1 — Make it feel good (the real work)
+- [ ] Import the **real RX-7 mesh**; swap `CarManager.buildCarModel` only.
+- [ ] Adopt a proven **constraint chassis** (A-Chassis or modern equivalent) for
+      real suspension/grip instead of the raw VehicleSeat. Do NOT hand-roll physics.
+- [ ] Tune driving feel: acceleration curve, grip, camera.
+- [ ] Sound: engine loop, boost, tire screech.
+**Exit test:** the RX-7 is genuinely fun to just drive around.
+
+## M2 — Race depth
+- [ ] Checkpoints + lap/segment timing (extend `RaceManager`).
+- [ ] Personal best times saved to profile.
+- [ ] A second race type (drag / point-to-point).
+- [ ] Countdown + results screen.
+
+## M3 — Content & progression polish
+- [ ] Flesh out the 25-car catalogue across tiers.
+- [ ] Car customization cosmetics (rims, wraps, neon) — visual only for MVP.
+- [ ] Daily missions (not just login): "win 3 races", "earn $5k".
+- [ ] Tutorial for the first 10 minutes.
+
+## M4 — Systems hardening
+- [ ] Leaderboards (OrderedDataStore: top rep, fastest times).
+- [ ] Anti-cheat pass 2 (validate race times against car stats).
+- [ ] DataStore stress test / backup-version restore drill.
+- [ ] Performance pass: StreamingEnabled tuning, part budget, mobile test.
+
+## M5 — Monetization (only after it's fun)
+- [ ] 2× Cash gamepass (the classic first product).
+- [ ] VIP membership (daily bonus, cosmetic-only exclusives).
+- [ ] Nitro/boost dev-products — **never** pay-to-win on ranked races.
+- [ ] Receipt handling via ProfileStore `LastSavedData`.
+
+## M6 — Traffic AI (deferred hardest system)
+- [ ] Start with **spline-following** dummy cars on fixed paths (cheap, no lag).
+      Only attempt true pathfinding AI if performance allows.
+- [ ] Spawn/despawn by distance to keep part count sane.
+
+---
+
+## Standing engineering rules
+- Every change must pass `stylua --check`, `selene`, and `rojo build` (CI enforces).
+- Keep the client dumb: it requests, the server decides. No exceptions for money.
+- Add new tunables to `GameConfig`, not scattered magic numbers.
+- Add a save key by adding it to `ProfileTemplate` (auto-reconciles); never remove
+  a key without a migration.
+- Test in Studio after every server change (ProfileStore uses a mock store there).