fix(hwfit): distinguish Apple Silicon bandwidth variants (#2564)

* fix: resolve Apple Silicon bandwidth variants

* fix(hwfit): preserve string lookup path in _lookup_bandwidth

* fix(hwfit): guard Apple bandwidth lookup against false GPU matches

Add "apple" not in gn check to _lookup_apple_bandwidth() so that
non-Apple GPUs with "m3"/"m4"/"m5" in their names (e.g. NVIDIA
Quadro M4 000) don't incorrectly match Apple bandwidth tiers.

Addresses @o3LL review comment on PR #2564.

tests/test_hwfit_apple_bandwidth.py

@@ -0,0 +1,40 @@
+from services.hwfit.fit import _lookup_bandwidth
+
+
+def test_m3_max_bandwidth_uses_gpu_cores():
+    assert _lookup_bandwidth({"gpu_name": "Apple M3 Max", "gpu_cores": 30}) == 300
+    assert _lookup_bandwidth({"gpu_name": "Apple M3 Max", "gpu_cores": 40}) == 400
+
+
+def test_m4_max_bandwidth_uses_gpu_cores():
+    assert _lookup_bandwidth({"gpu_name": "Apple M4 Max", "gpu_cores": 32}) == 410
+    assert _lookup_bandwidth({"gpu_name": "Apple M4 Max", "gpu_cores": 40}) == 546
+
+
+def test_m5_max_bandwidth_uses_gpu_cores():
+    assert _lookup_bandwidth({"gpu_name": "Apple M5 Max", "gpu_cores": 32}) == 460
+    assert _lookup_bandwidth({"gpu_name": "Apple M5 Max", "gpu_cores": 40}) == 614
+
+
+def test_apple_max_bandwidth_falls_back_conservatively_without_gpu_cores():
+    assert _lookup_bandwidth({"gpu_name": "Apple M3 Max"}) == 300
+    assert _lookup_bandwidth({"gpu_name": "Apple M4 Max"}) == 410
+    assert _lookup_bandwidth({"gpu_name": "Apple M5 Max"}) == 460
+
+
+def test_fixed_apple_bandwidth_entries_include_updated_m5_values():
+    assert _lookup_bandwidth({"gpu_name": "Apple M5 Pro"}) == 307
+    assert _lookup_bandwidth({"gpu_name": "Apple M5"}) == 153
+
+
+def test_non_apple_gpu_does_not_match_apple_bandwidth():
+    """NVIDIA Quadro M4 000 should NOT match Apple bandwidth lookup."""
+    assert _lookup_bandwidth({"gpu_name": "NVIDIA Quadro M4 000"}) is None
+    assert _lookup_bandwidth({"gpu_name": "NVIDIA Quadro M3 000"}) is None
+    assert _lookup_bandwidth({"gpu_name": "NVIDIA Quadro M5 000"}) is None
+
+
+def test_non_apple_gpu_with_cores_does_not_match():
+    """NVIDIA GPU with core count should not match Apple bandwidth."""
+    assert _lookup_bandwidth({"gpu_name": "NVIDIA GeForce RTX 4090", "gpu_cores": 128}) is None
+    assert _lookup_bandwidth({"gpu_name": "AMD Radeon RX 9070 XT", "gpu_cores": 64}) is None