@spec collect_repeated([String.t()], String.t()) :: [String.t()]

Collects all values for a repeated --flag from raw args.

Supports both --flag value and --flag=value forms.

@spec parse_align(String.t() | atom() | nil) :: :left | :center | :right

Parses an alignment string into an atom.

@spec parse_color(String.t() | nil) ::
  {:ok, {byte(), byte(), byte()}} | {:error, term()} | nil

Parses a color string using the Drawer colour system. Returns {:ok, {r,g,b}} or {:error, reason}.

@spec parse_color_list(String.t() | nil) ::
  {:ok, [tuple()]} | {:error, String.t()} | nil

Parses a semicolon-separated list of colors. Returns {:ok, [{r,g,b}, ...]} or {:error, message}.

@spec parse_color_opt(String.t() | nil) :: {byte(), byte(), byte()} | nil

Parses a color and returns the RGB tuple, or prints error to stderr and returns nil.

@spec parse_env_pair(String.t()) :: {atom(), String.t()} | nil

Parses a KEY=VALUE string into a tuple.