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/gate.toml

@@ -0,0 +1,8 @@
+name = "City Gate"
+description = """\
+Towering iron-reinforced wooden gates mark the southern edge of town. \
+Guards in dented armor lean on their spears, watching the dusty road \
+that stretches into the wilderness beyond."""
+
+[exits]
+north = "town:dark_alley"