Initial commit: Transcience MVP

Top-down twin-stick bullet-hell, Godot 4.7, server-authoritative dedicated
server with client-side prediction. Clients send input only; the server
resolves every hit for both players and enemies (no PvP).

- SimWorld: whole simulation as plain RefCounted objects (no nodes, no
  physics server), ~0.24ms/tick at peak load -- runs headless for free and
  drives 78 tests in under a second
- BulletPool: struct-of-arrays bullet storage, replicated as spawn/despawn
  events rather than per-tick state
- Emitter framework (Ring/AimedSpread/WallGap/ArcSweep) shared by trash
  enemies and bosses -- a new boss is data in src/content/content.gd, no
  simulation changes
- The Warden of the Fold: stationary 4-phase boss built entirely on that
  format
- Lobby hub with a portal into on-demand dungeon instances; one process
  hosts the hub plus every concurrent dungeon
- Emergency escape: 3s server-owned channel, cancelled by damage
- tools/check.sh, test.sh (GUT), smoke.sh (real server + bot clients over
  ENet), bench.gd; git hooks wired to the same scripts
- docs/ARCHITECTURE.md, NETCODE.md, WORKFLOW.md, ROADMAP.md

docs/ROADMAP.md

@@ -0,0 +1,56 @@
+# Roadmap
+
+## Built
+
+| MVP requirement | State |
+| --- | --- |
+| Top-down 2D twin-stick bullet hell | Movement, aim, fire, i-frames, death and respawn; MultiMesh bullet rendering. |
+| Multiplayer with server-side hit validation | Authoritative dedicated server; clients send input only; all hits resolved server-side for both players and enemies. No PvP. |
+| Simple, predictable enemies | Drifter, Turret, Stalker, plus a lobby dummy. Five movement behaviours, all closed-form. |
+| Stationary boss, adaptable format | The Warden of the Fold: four phases, data-defined. A new boss is one function and zero simulation changes. |
+| Lobby hub with dungeon entry | Persistent lobby instance, portal, party forming window, dungeons opened on demand. |
+| Emergency escape | Three-second channel, cancelled by damage or release, server-owned. |
+
+78 tests plus an end-to-end smoke test over a real socket.
+
+## Next, in rough order of value
+
+**1. Make the dungeon a place.** Right now it is one arena and three stages.
+Rooms, doors, and a `SimWorld` with static geometry — which means adding a
+collision representation for walls (segment-vs-circle for players, segment
+crossing for bullets) since there is no physics engine to lean on.
+
+**2. Art and feel.** Everything is drawn with `draw_circle` and a generated dot
+texture. Sprites, hit flashes, screen shake, muzzle flashes, death effects, and
+sound. None of it touches the simulation — this is entirely `src/view/`.
+
+**3. A second boss.** The format claims to be reusable; the way to find out is
+to use it. A mobile boss will exercise `BossDef.stationary`, which the runtime
+already reads but no content uses yet.
+
+**4. Progression.** Loot, character stats, persistence. Needs a decision on
+storage: for a dedicated server, player state belongs server-side in a database,
+not in a client save file.
+
+**5. Netcode hardening.** In the order they will actually matter:
+   - DTLS on `ENetMultiplayerPeer` before any public server.
+   - Authentication; `peer_names` is currently client-supplied and trusted for
+     display only, which is fine now and will not be once there is progression.
+   - Snapshot delta compression, once enemy counts grow.
+   - Interest management inside an instance, once arenas are larger than a
+     screen.
+
+**6. Scale.** The simulation costs ~1.4% of a core per instance, so the ceiling
+is bandwidth and process supervision, not CPU. A shard manager that runs several
+server processes behind a lobby-of-lobbies is the shape, but it is premature
+until there is a game to fill it.
+
+## Deliberately not done
+
+- **Lag compensation.** Discussed in [NETCODE.md](NETCODE.md): rewinding for a
+  shooter's view would mean a player who dodged still gets hit, which is the
+  wrong trade for this genre.
+- **Pattern-level bullet replication.** A large bandwidth win that couples the
+  client to emitter behaviour. Not worth it until bandwidth binds.
+- **`MultiplayerSynchronizer` / `MultiplayerSpawner`.** Right tools, wrong shape
+  for a bullet hell. See [ARCHITECTURE.md](ARCHITECTURE.md).