Minify stdlib parameter names

[brianp]

Every stdlib function should use the shortest, easily understood parameter name possible.

For example, say(message: ...) becomes say(msg: ...). The goal is brevity without sacrificing clarity. A developer reading the call site should still immediately know what the argument means.

Guidelines

• Prefer common, well-known abbreviations: msg, val, fmt, src, dst, buf, len, idx, fn, cb, sep, delim, str, num, err, cmd, dir, env, cfg, ctx, opt, max, min
• Single-word names that are already short can stay as-is (e.g. name, path, key, port)
• When two abbreviations are equally clear, pick the shorter one
• Don't abbreviate to the point of confusion. n is fine for a count in a math context, but name shouldn't become n

Scope

All public stdlib functions across every std/* module. This is a breaking change for any code using named arguments, so it should land as a single pass.