feat: Verbatim MVP - terminal renderer, cellular automaton, Verlet physics

- World: 250x250 grid with 14 materials (sand, water, lava, stone, wood, etc.)
- Physics: cellular automaton for materials + Verlet solver for entities
- Entity: multi-cell humanoid (7 sub-bodies with distance constraints)
- Render: terminal renderer with ANSI colors and diff-based updates
- Game loop: fixed 60Hz timestep with accumulator pattern
- Input: WASD movement, number keys for material painting

Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "verbatim"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+crossterm = "0.28"
+clap = { version = "4", features = ["derive"] }
+
+[profile.release]
+opt-level = 3
+lto = true
+codegen-units = 1