Feature Request: Configuration file support for default options

Problem

Using the same flags repeatedly is tedious:

# Python projects
files-to-prompt . --ignore "*.pyc" --ignore "__pycache__" --ignore ".venv" --ignore "*.egg-info" --ignore ".pytest_cache"

# Node projects  
files-to-prompt . --ignore "node_modules" --ignore "dist" --ignore "*.min.js" --ignore "package-lock.json"

Proposed Solution

Support configuration files to set defaults:

• .files-to-prompt.toml in project directory
• ~/.config/files-to-prompt/config.toml for user defaults
• CLI args override config values

Example

.files-to-prompt.toml:

[defaults]
ignore = [
    "*.pyc",
    "__pycache__",
    ".venv",
    "*.egg-info",
    ".pytest_cache",
]
extensions = ["py", "md", "toml"]

Usage:

files-to-prompt .                      # Uses config
files-to-prompt . --ignore-gitignore   # CLI overrides config
files-to-prompt . --no-config           # Skips config

Implementation Proposal

• TOML format (built-in for Python 3.11+, tomli for older versions)
• Config discovery walks up directories (like .gitignore)
• Precedence: CLI > project config > user config > defaults
• All CLI options supported in config