ggml: add Q1_0 1-bit quantization support (CPU) (#21273)

* ggml: add Q1_0 and Q1_0_g128 1-bit quantization support (CPU)

* add generic fallback for x86

* remove Q1_0 (group size 32)

* rename Q1_0_g128 => Q1_0

* fix Q1_0 LlamaFileType Enum

* Fix trailing spaces; add generic fallback for othre backends

* Apply suggestions from code review

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

* fix /r/n spacing + arch-fallback

---------

Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>

gguf-py/gguf/constants.py

@@ -3996,6 +3996,7 @@ class GGMLQuantizationType(IntEnum):
     TQ2_0   = 35
     MXFP4   = 39
     NVFP4   = 40
+    Q1_0    = 41
 
 
 class ExpertGatingFuncType(IntEnum):
@@ -4049,6 +4050,7 @@ class LlamaFileType(IntEnum):
     MOSTLY_TQ2_0         = 37  # except 1d tensors
     MOSTLY_MXFP4_MOE     = 38  # except 1d tensors
     MOSTLY_NVFP4         = 39  # except 1d tensors
+    MOSTLY_Q1_0          = 40  # except 1d tensors
 
     GUESSED              = 1024  # not specified in the model file
 
@@ -4161,6 +4163,7 @@ GGML_QUANT_SIZES: dict[GGMLQuantizationType, tuple[int, int]] = {
     GGMLQuantizationType.TQ2_0:   (256, 2 + 64),
     GGMLQuantizationType.MXFP4:   (32, 1 + 16),
     GGMLQuantizationType.NVFP4:   (64, 4 + 32),
+    GGMLQuantizationType.Q1_0:    (128, 2 + 16),
 }