experimental: remove Tekton Doors entirely

- Delete portal_mode_manager.gd, portal_door.gd, portal_door.tscn
- Strip all Tekton Doors logic from main.gd, player.gd, lobby.gd,
  lobby_room.gd, lobby_manager.gd, camera_context_manager.gd,
  music_manager.gd, tekton.gd, enhanced_gridmap.gd,
  playerboard_manager.gd, special_tiles_manager.gd
- Remove TK enum (TEKTON_DOORS=2), mode_config schema, arena area
- Update tests: 3 modes instead of 4
- Strip HowToPlay tab from main.tscn

wiki/home.md

@@ -0,0 +1,16 @@
+# Tekton Dash Armageddon
+
+<a id="top"></a>
+
+- [Game Modes](./Game-Modes.-) — Full per-mode reference: Stop n Go, Tekton Doors, Candy Pump Survival, Freemode
+- [Architecture - Client](./Architecture-Client) — Godot client code structure, managers, scenes, player controller
+- [Architecture - Server](./Architecture-Server) — Nakama Lua backend topology, auth flow, wallet economy, admin roles
+- [Nakama Server API](./Nakama-Server-API) — Full per-function RPC reference with params, returns, errors
+- [Patch Release Workflow](./Patch-Release-Workflow.-) — Hot patch and binary release CI/CD pipelines
+- [Skin Creation Workflow](./Skin-Creation-Workflow.-) — Skin material authoring, catalog registration, gacha prizes
+- [Nakama Deployment](./Nakama-Deployment.-) — Push Lua updates to Nakama server
+- [SSH Setup — Linux](./SSH-Setup-Linux)
+- [SSH Setup — macOS](./SSH-Setup-macOS)
+- [SSH Setup — Windows](./SSH-Setup-Windows)
+
+[Back to top](#top)