Make the CLI speak git's dialect

Make the CLI speak git's dialect

The flags were wrong in the way that matters: `-title` is a single-dash long
option, which anything that thinks like getopt reads as `-t -i -t -l -e`. Git's
conventions (gitcli(7)) are `--long`, `-o`, and no bundling, so this replaces the
parser and every call site.

Now:

- `--long value`, `--long=value`, `-o value`, `-ovalue`.
- Short options are never bundled: `-ab` is not `-a -b`. For an option that takes
  a value, `-mm` is the stuck form and means the value "m"; for a boolean, a
  bundle is an error.
- `-o=value` is refused with a message pointing at `-ov` or `--long=v`, because
  silently taking "=value" is the kind of thing that costs an hour later.
- Options come before arguments, and an option after an argument is an error
  naming the argument rather than something to guess about.
- `--` and `--end-of-options` end option parsing; `-h`/`--help` print the
  subcommand's usage and exit 0; usage mistakes exit 129, as git does.
- `-m`/`-F` mirror `git commit`: mutually exclusive, `-F -` reads stdin.
- `-l` is repeatable; comma-separated still works for convenience.
- `issue list --format` takes `%(id)`, `%(shortid)`, `%(state)`, `%(author)`,
  `%(title)`, `%(labels)`, `%(created)` for scripts.
- `vole.author` is consulted before `user.name` for the default author.

Two bugs came out of the change, both caught by tests rather than by reading:

- The new parser stored `--config` as an ordinary value and never copied it to
  the path the commands actually use, so every command silently fell back to
  ./vole.toml. A test that rebuilds an index in a temp directory failed loudly.
- The integration test itself passed `-config`, which the new parser read as
  `-c onfig` — exactly the ambiguity this commit removes, in the wild.

Verified by hand against a live instance: repeatable `-l`, stuck `--title=x`,
`--format`, `issue comment -m text <id>` accepted, `issue comment <id> -m text`
refused with exit 129 and "options must come before arguments", `-h` exiting 0,
and a missing option value exiting 129.