fix(dotnet,go,search): make the probes and lists say what they mean

`detect_test_runner_mode_in_dir`'s `scan_dir` promised tests an isolated
directory but only the project scan honoured it: the `global.json` and
`Directory.Build.props` walks still started from the real process cwd, so six
tests that pass a tempdir were decided by whatever the developer's checkout sat
under. All three probes start from `scan_dir` now, with a test that puts a
`global.json` above the scanned directory.

golangci listed the nine `--output.<format>.path` sinks twice, in the
value-taking predicate and again in the collision check, with nothing tying
them together; there is one list now, read by both.

Three comments were describing something other than the code: dotnet's
value-taking table called itself "not exhaustive" while the project scan
documented that it *required* exhaustiveness (it does not -- the extension
filter exists for exactly that reason); `has_trx_logger_arg`'s scoping now
carries the evidence for why it differs from its neighbours (`dotnet test
--help`: arguments after `--` go "to the application that is being run"); and
`stash_show_wants_patch`'s "nothing takes a value" predicate is git's actual
grammar for that question, not a placeholder.

`has_format_flag` goes through the module's shared tokenizer, so it cannot
classify an argument differently from `extract_pattern_path`.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>