Add rustdoc and inline comments throughout; update CLAUDE.md style guide

All public types, fields, and functions in game.rs and map_file.rs now
have /// doc comments. main.rs has /// on App and draw_glyph plus inline
comments explaining the input/render pipeline. CLAUDE.md records the
expectation that generated code includes comments.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -6,6 +6,12 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 `viberogue` is a ZZT-inspired game-making system written in Rust (edition 2024). The goal is a system where players can create games using a scripting language, similar to the classic DOS game ZZT. It uses **Rhai** for scripting (WASM-compatible, sandboxed, pure Rust).
 
+## Code style
+
+- Add `///` rustdoc comments to every `pub` type, field, and function. The user reads rustdoc in their IDE to understand the code while making changes.
+- Add inline `//` comments inside non-trivial function bodies to explain the *why* of each logical step — especially in `update` loops, rendering math, and conversion logic.
+- Keep comments accurate: update them when the code they describe changes.
+
 ## Commands
 
 ```bash