Configuration file support

Without a config file, users must pass --api-key, --format, --output-dir, and --region on every single invocation. That friction drives them toward shell aliases that are fragile, .env files that aren't portable, and wrapper scripts that become undocumented infrastructure. ISO 25010:2011 usability.operability scores CLIs on whether persistent preferences can be set once and forgotten. A CLI that requires 6 flags per invocation is not operationally usable in real workflows — teams will script around it rather than into it, breaking the tool's intended composability.

Add config file discovery using cosmiconfig (Node.js) or a standard ~/.config location (Python/Go). CLI flags must always override config file values:

import { cosmiconfig } from 'cosmiconfig'

const explorer = cosmiconfig('mytool')
const result = await explorer.search()   // finds .mytoolrc, mytool.config.js, etc.
const fileConfig = result?.config ?? {}

// CLI flags override config — spread order matters
const config = { ...fileConfig, ...cliFlags }

import tomllib
from pathlib import Path

def load_config() -> dict:
    for loc in [Path('mytool.toml'), Path.home() / '.config' / 'mytool' / 'config.toml']:
        if loc.exists():
            with open(loc, 'rb') as f:
                return tomllib.load(f)
    return {}  # no config file is not an error

Document which config file locations are checked in --help output or a mytool config --locations subcommand.