adding more nodes

docs/nodes/Lattice Measurement.md

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+# Lattice Measurement
+
+Detect and measure periodic lattice structures from ACF or FFT peak positions. Reports lattice vectors and angles. Equivalent to Gwyddion's measure_lattice.c module.
+
+## Inputs
+
+| Name | Type | Required | Description |
+|------|------|----------|-------------|
+| field | DATA_FIELD | Yes | Input field with periodic structure |
+
+## Outputs
+
+| Name | Type | Description |
+|------|------|-------------|
+| correlation | DATA_FIELD | ACF or FFT magnitude used for detection |
+| measurements | RECORD_TABLE | Detected lattice vectors, spacings, and angle |
+
+## Controls
+
+| Name | Type | Default | Description |
+|------|------|---------|-------------|
+| method | dropdown | acf | Detection method: acf (autocorrelation) or fft (Fourier transform) |
+
+## Notes
+
+- ACF method finds the strongest off-center peaks in the 2D autocorrelation. Works well for real-space periodic structures.
+- FFT method finds peaks in the power spectrum. Better for weak periodicity or noisy data.
+- Reports up to two lattice vectors (a, b), their magnitudes, and the angle between them.
+- For best results, the field should contain at least 3–4 complete periods in each direction.