Initial commit: SSH MUD server with data-driven world

Rust-based MUD server accepting SSH connections on port 2222.
Players connect with any SSH client, get dropped into a
data-driven world loaded from TOML files at startup.

Binary systems: SSH handling (russh), command parser, game state,
multiplayer broadcast, ANSI terminal rendering.

Data layer: world/ directory with regions, rooms, NPCs, and objects
defined as individual TOML files — no recompile needed to modify.

Commands: look, movement (n/s/e/w/u/d), say, who, help, quit.
Made-with: Cursor

world/town/rooms/dark_alley.toml

@@ -0,0 +1,9 @@
+name = "Dark Alley"
+description = """\
+A narrow passage between crumbling stone walls. Puddles of dubious origin \
+dot the ground. Shadows pool in doorways, and you catch the faint sound \
+of whispered conversation from somewhere above."""
+
+[exits]
+north = "town:town_square"
+south = "town:gate"