feat: 🎉 Vectors na Vectors, the begining

Translate 1536 <-> 768 , 3072 <-> 2048

pkg/adapter/projection.go

@@ -0,0 +1,32 @@
+package adapter
+
+import "fmt"
+
+type projectionAdapter struct {
+	sourceDim int
+	targetDim int
+	matrix    [][]float32
+}
+
+func (a *projectionAdapter) SourceDim() int { return a.sourceDim }
+func (a *projectionAdapter) TargetDim() int { return a.targetDim }
+
+func (a *projectionAdapter) Adapt(vec []float32) ([]float32, error) {
+	if len(vec) != a.sourceDim {
+		return nil, fmt.Errorf("projection adapt: %w: got %d, want %d", ErrDimMismatch, len(vec), a.sourceDim)
+	}
+	return L2Norm(matVecMul(a.matrix, vec)), nil
+}
+
+// matVecMul computes m·v where m is [rows][cols] and v has len cols.
+func matVecMul(m [][]float32, v []float32) []float32 {
+	out := make([]float32, len(m))
+	for i, row := range m {
+		var sum float32
+		for j, val := range row {
+			sum += val * v[j]
+		}
+		out[i] = sum
+	}
+	return out
+}