Give the stroke pattern one mode and design.yaml tuning

The twelve experimental modes collapse to camera_compensated_width, whose ten
knobs now come from a `stroke_pattern` block, and the PNG-only binary-preview
command goes with them as a strict subset of stroke-texture.

Verified: output is byte-identical at the defaults against the previous code, a
knob change is visible in the artifacts, the suite is green and the doc gate is
clean.

sensors/finger-xynova/r01/design.yaml

@@ -88,6 +88,26 @@ texture_patch_views:
   print:
     base_fill: owned           # white ground, already split by the seam
 
+# Random Stroke Pattern (`orisys-design stroke-texture`).
+# One mode: a capsule of `width` swept `length`, rotated per cell, sized from the camera
+# cell's print-page footprint so a cell the projection stretches gets a proportionally
+# larger mark. `--seed` / `--min-cell-pixels` / `--camera-width-fraction` override per run.
+# Field reference: the inline comments below. These defaults are an image-space experiment,
+# not a print master: `width_min_mm: 0.11` is below the demonstrated 0.2 mm dot (see
+# docs/probe-findings.md). The resolved values are written to _stroke_pattern_params.json and
+# recorded in the stroke-texture manifest, which is what makes a run reproducible.
+stroke_pattern:
+  seed: 7                    # per-cell offset and angle; reproducible
+  min_cell_pixels: 20        # cells smaller than this are skipped
+  jitter_fraction: 0.66      # mark offset range inside its cell; 0 pins to the centre
+  angle_span_deg: 180.0      # rotation range; 0 makes every stroke parallel
+  width_fraction: 0.50       # width = clamp(cell footprint x this, width_min_mm, width_max_mm)
+  width_min_mm: 0.11
+  width_max_mm: 0.28
+  length_ratio: 2.4          # length = ratio x width
+  coverage_cap: 0.45         # skip a mark that would exceed this local fill
+  neighbourhood_mm: 0.5      # radius of the local-fill neighbourhood
+
 # Advisory only: reports a verdict, never blocks generation or changes exit codes.
 # Millimetres are measured on the vector page declared above.
 printability:

sensors/finger/r01/design.yaml

@@ -94,6 +94,26 @@ texture_patch_views:
   print:
     base_fill: owned           # white ground, already split by the seam
 
+# Random Stroke Pattern (`orisys-design stroke-texture`).
+# One mode: a capsule of `width` swept `length`, rotated per cell, sized from the camera
+# cell's print-page footprint so a cell the projection stretches gets a proportionally
+# larger mark. `--seed` / `--min-cell-pixels` / `--camera-width-fraction` override per run.
+# Field reference: the inline comments below. These defaults are an image-space experiment,
+# not a print master: `width_min_mm: 0.11` is below the demonstrated 0.2 mm dot (see
+# docs/probe-findings.md). The resolved values are written to _stroke_pattern_params.json and
+# recorded in the stroke-texture manifest, which is what makes a run reproducible.
+stroke_pattern:
+  seed: 7                    # per-cell offset and angle; reproducible
+  min_cell_pixels: 20        # cells smaller than this are skipped
+  jitter_fraction: 0.66      # mark offset range inside its cell; 0 pins to the centre
+  angle_span_deg: 180.0      # rotation range; 0 makes every stroke parallel
+  width_fraction: 0.50       # width = clamp(cell footprint x this, width_min_mm, width_max_mm)
+  width_min_mm: 0.11
+  width_max_mm: 0.28
+  length_ratio: 2.4          # length = ratio x width
+  coverage_cap: 0.45         # skip a mark that would exceed this local fill
+  neighbourhood_mm: 0.5      # radius of the local-fill neighbourhood
+
 # Advisory only: reports a verdict, never blocks generation or changes exit codes.
 # Millimetres are measured on the vector page declared above.
 printability: