Set up mix_gleam archive, gleam_stdlib, and gleeunit deps. Add Gleam
compiler to all Dockerfiles, CI workflows, nix shell, and .tool-versions.
Rewrite Numeric, QueryHelpers, and URLValidator from Elixir to Gleam with
full ExUnit test coverage. Update all callers to use the Gleam modules
directly via :towerops@module syntax. Remove duplicate sanitize_like/1
private functions in snmp.ex and trace.ex.
Reviewed-on: graham/towerops-web#98
