fix(hwfit): filter non-GGUF models on Windows (#2530)

Odysseus only supports llama.cpp on Windows (vLLM/SGLang are
explicitly blocked). llama.cpp requires GGUF, so AWQ/GPTQ/FP8
safetensors models without a GGUF alternate should not be
recommended in the Cookbook on Windows hosts.

Changes:
- hardware.py: add 'platform': 'windows' to _detect_windows()
  so downstream logic can identify Windows hosts.
- fit.py: include is_windows in the existing GGUF-only filter
  alongside apple_silicon and consumer_amd.
- tests: add test_hwfit_windows.py with regression tests.

Fixes #122, #614 (root cause: unservable models recommended).

services/hwfit/fit.py

@@ -576,6 +576,7 @@ def rank_models(system, use_case=None, limit=50, search=None, sort="score", quan
     system_backend = (system.get("backend") or "").lower()
     apple_silicon = system_backend in ("mps", "metal", "apple")
     rocm = system_backend == "rocm"
+    is_windows = system.get("platform") == "windows"
 
     # Consumer AMD Radeon (RDNA, gfx10/11/12): the practical local serving path
     # is GGUF via llama.cpp. vLLM/SGLang on ROCm are validated for datacenter
@@ -615,7 +616,11 @@ def rank_models(system, use_case=None, limit=50, search=None, sort="score", quan
         # servable path, so a model needs a real GGUF to be recommended.
         # Otherwise the Cookbook rates vLLM-only AWQ/GPTQ builds "GOOD" on a
         # Radeon that can't actually serve them.
-        if (apple_silicon or consumer_amd) and not (m.get("is_gguf") or m.get("gguf_sources")):
+        #
+        # Windows is the same: Odysseus only supports llama.cpp on Windows,
+        # which requires GGUF. vLLM/SGLang are explicitly blocked, so AWQ/GPTQ
+        # models without a GGUF source are unservable there.
+        if (apple_silicon or consumer_amd or is_windows) and not (m.get("is_gguf") or m.get("gguf_sources")):
             continue
 
         # Format filter: AWQ tab -> only AWQ models, FP4 tab -> FP4-family models, etc.

services/hwfit/hardware.py

@@ -539,6 +539,7 @@ def _detect_windows():
             "backend": d.get("gpu_backend", "cpu_x86"),
             "homogeneous": True,
             "gpu_error": None,
+            "platform": "windows",
         }
         # PowerShell only reports aggregate GPU info, not per-card detail, so we
         # can't tell a mixed box from a uniform one here — assume one homogeneous