Rewrite in gleam

[nwjlyons]

Summary
This PR ports the game domain logic from Elixir to Gleam while preserving the existing Phoenix-facing APIs and behavior.

What Changed

• Added Gleam project/tooling configuration:
• Pinned gleam 1.14.0 in .tool-versions.
• Added gleam.toml and generated manifest.toml.
• Updated mix.exs to compile Gleam via mix_gleam archive, include Gleam Erlang output paths, and run gleam.deps.get as part of deps.get.
• Added Gleam runtime deps in mix.exs/mix.lock: gleam_stdlib, gleam_otp, gleam_erlang.
• Added /build/ to .gitignore for Gleam build artifacts.
• Implemented core logic in Gleam modules under src/:
• src/robot_race_game.gleam
• src/robot_race_robot.gleam
• src/robot_race_id.gleam
• src/robot_race_game_id.gleam
• src/robot_race_robot_id.gleam
• src/robot_race_stats.gleam
• Reworked Elixir modules into compatibility wrappers/delegators:
• lib/robot_race/game.ex
• lib/robot_race/robot.ex
• lib/robot_race/id.ex
• lib/robot_race/game_id.ex
• lib/robot_race/robot_id.ex
• lib/robot_race_web/stats_server.ex
• Formatting-only changes:
• config/config.exs
• lib/robot_race_web/templates/error/error.html.heex

Behavior/Compatibility

• Existing public Elixir APIs are preserved.
• Phoenix/LiveView layer remains unchanged.
• Game state logic now executes in Gleam, with Elixir <-> Gleam conversion at module boundaries.