fix: find and jq honour -- as end-of-options

[davydog187]

Fixes #90

Follow-up from #89 / #83. StdinOperand.split_end_of_options/1 already covered most file-operand commands, but find and jq still mishandled --.

User-visible behavior

# before
$ find -- -foo
find: unknown predicate '-foo'    # rc=1

$ printf '{"k":1}\n' | jq -- .
jq: .: Is a directory             # `.` opened as a path

# after
$ find -- -foo
-foo
-foo/x                            # rc=0 when that path exists

$ printf '{"k":1}\n' | jq -- .
{
  "k": 1
}

jq . -- FILE is unchanged. JustBash.exec/2 does not raise.

GNU find still treats find -- -foo as a predicate (a path starting with - ends the starting-point list). This change follows the #90 / ln.ex reading: -- ends parse and the remainder are operands, which is the POSIX reason -- exists.

GNU jq: -- only ends options. The first remaining positional is the filter (default .), then the file.

Changes

• find calls split_end_of_options/1 and appends the remainder as paths, so find -- -foo searches -foo.
• jq collects leftover positionals from before -- and concatenates them with the extra tokens after it: filter, then file. jq -- . no longer opens . as a path.
• Tests for find -- -foo, jq -- ., and extra -- placements (only arg, file named --, -- between two operands).

Type of Change

• Bug fix (non-breaking change which fixes an issue)

Testing

• Added new tests
• All existing tests pass

Local gates:

mix compile --warnings-as-errors
mix format --check-formatted
mix credo            # clean
mix credo --strict   # only the pre-existing apply/2 test fixture
mix test
# Finished in 39.1 seconds
# 2 doctests, 62 properties, 5488 tests, 0 failures (5 excluded)
mix docs --warnings-as-errors
mix dialyzer
# Total errors: 13, Skipped: 13, Unnecessary Skips: 0

Checklist

• My code follows the style guidelines of this project
• I have run mix format
• I have run mix credo and addressed any issues
• I have added tests that prove my fix is effective
• New and existing tests pass locally with my changes
• I have updated the CHANGELOG.md