fix(query): don't query the terminal on handles that are not terminals

[willemkokke]

---

Found while tracking down a start-up hang in tea, the Gitea CLI,
which blocks forever on Windows when its stdio is redirected: https://gitea.com/gitea/tea/issues/1053

The problem

On Windows, BackgroundColor replaces any handle that is not a terminal with CONIN$/CONOUT$
and queries the console instead:

if runtime.GOOS == "windows" {
    if !term.IsTerminal(in.Fd()) {
        f, err := os.OpenFile("CONIN$", os.O_RDWR, 0o644)
        ...
        in = f
    }
    ...
}

So a program whose stdio is redirected — a Windows service, a CI job — writes an OSC 11 query to a
console nobody is watching, and then waits for a reply that never comes. Redirecting stdio does not
protect you, which is surprising: on Unix the same function returns input/output is not a terminal
and gives up.

There is a 2 second timeout on the read, but it does not currently fire, because the CONIN$ handle
this code creates defeats ultraviolet's cancel reader. That is a separate bug and I have opened
charmbracelet/ultraviolet#138 for it. With that fixed, the behaviour here becomes a 2 second stall per call instead of
a hang — better, but still wrong for a program that is only trying to print a version string.

The fix

Do what Unix already does: if the handles the caller passed are not terminals, say so and return.

The caller chose those handles. If output is going to a pipe, the console's background colour is
not the question being asked, and adaptive colour has nothing to adapt to. A caller that genuinely
wants to talk to the console can open CONIN$/CONOUT$ and pass them in — the API takes explicit
handles, so that option is still there.

The Windows branch stays, because console input and output are separate handles and must be queried
as a pair rather than treating either one as bidirectional.

I realise this deletes a deliberate special case, so I am happy to be told the intent was something
I have missed. If the redirected-stdio path needs to stay, the alternative is to keep it and rely on
the ultraviolet fix to bound it — but then every non-interactive Windows program pays a 2 second
stall on start-up, and via the compat package it pays it before main() runs.

Tests

query_test.go, cross-platform, using os.Pipe() handles:

• BackgroundColor must report that pipes are not terminals, and return rather than wait
• HasDarkBackground must fall back to its documented dark default

The first fails against main on Windows — it returns no error, because it went and queried the
console anyway. Both pass with the fix. Full suite passes.

Unrelated, but worth flagging

compat runs this query from package-level vars:

var (
    HasDarkBackground = lipgloss.HasDarkBackground(os.Stdin, os.Stdout)
    Profile           = colorprofile.Detect(os.Stdout, os.Environ())
)

Importing that package for a type — compat.AdaptiveColor — therefore makes a program query the
terminal before main() runs. That is how tea ended up hanging on tea --version. It cannot be
made lazy without changing the exported bool to a function, so I have not touched it here, but it
seems worth a look.