`SPLUNK_HOME` absolute-path check in `splunklib.ai.tools` fails on Windows

Describe the bug

_splunk_home() in splunklib/ai/tools.py validates that SPLUNK_HOME is an absolute path via splunk_home.startswith("/"). This check is POSIX-only. On Windows, SPLUNK_HOME is a drive-letter path (e.g. C:\Program Files\Splunk), which never starts with / even though it is a valid absolute path. As a result, _splunk_home() — and anything built on it, such as locate_app() — unconditionally raises RuntimeError("SPLUNK_HOME is not absolute") on Windows, regardless of the actual value of SPLUNK_HOME. This makes the splunklib.ai.tools module entirely unusable on Windows.

To Reproduce

1. On a Windows host, set a valid absolute SPLUNK_HOME, e.g.:

   set SPLUNK_HOME=C:\Program Files\Splunk
   

2. Run:

   from splunklib.ai.tools import locate_app
   locate_app()
   

   (or call _splunk_home() directly, or invoke anything in the SDK that depends on it, such as an app built with splunklib.ai.tools)
3. Observe:

   RuntimeError: SPLUNK_HOME is not absolute
   

   even though SPLUNK_HOME is a correctly-formed absolute Windows path.

Expected behavior

_splunk_home() should recognize Windows absolute paths (drive-letter paths, UNC paths) as valid — e.g. by using os.path.isabs(splunk_home) instead of splunk_home.startswith("/"). Any SDK functionality depending on SPLUNK_HOME should work identically on Windows and POSIX systems given a correct value.

Logs or Screenshots

RuntimeError: SPLUNK_HOME is not absolute

Raised from:

def _splunk_home() -> str:
    splunk_home = os.environ.get("SPLUNK_HOME", "/opt/splunk")
    if not splunk_home.startswith("/"):
        raise RuntimeError("SPLUNK_HOME is not absolute")
    return splunk_home

Splunk (please complete the following information):

• Version: 10.4.2
• OS: Windows Server 2022 (build 20348)
• Deployment: single-instance

SDK (please complete the following information):

• Version: 3.0.0
• Language Runtime Version: Python 3.13.11
• OS: Windows Server 2022 (build 20348)

Additional context

• The default fallback value ("/opt/splunk" when SPLUNK_HOME is unset) is also POSIX-only and would need a Windows-aware equivalent, or the fallback should be removed in favor of requiring an explicit value.
• This affects any app that vendors or depends on splunklib.ai.tools and is deployed on Windows — the failure is unconditional and unrelated to app configuration, credentials, or SPLUNK_HOME's actual correctness.

Inizia in splunklib/ai/tools.py, in _splunk_home(), quindi segui locate_app() e gli altri chiamanti che dipendono da esso. Verifica il comportamento dei percorsi assoluti per le lettere di unità Windows e i percorsi UNC, così come per i percorsi POSIX, e conferma che i valori Windows SPLUNK_HOME validi non generino più errori, mentre quelli non validi continuino a generarli.