Handwriting-like stroke order, row tuning, and pen-up metrics for G-code export

[RealBuddy]

This branch delivers a single, opinionated stroke-ordering pipeline for Samsung Notes → GRBL G-code, tools to measure and tune it, and a sensible default row scale from optimization on a sample note.

Stroke ordering

• One algorithm replaces the previous split between “global greedy” and “ruled-rows chain”: ruled rows (top-to-bottom), then horizontal bands inside each row (word-sized X gaps), greedy chain per band with backward-X penalty, debris (small marks) attached to the nearest band and drawn after that band.
• Carriage hint on a new row: first stroke of the next row prefers a pen-down near extra lines × intra-line slack below the previous row’s bottom.
• Legacy modes removed: --ruled-rows-order and order_strokes_writing_mode are gone; public entry is order_strokes().

Tuning & quality

• RULED_LINE_ROW_HEIGHT_SCALE default set to 1.1 after --optimize-row-scale on the sample (min total pen-up XY travel for that file).
• StrokeOrderTuning dataclass (x-gap factor, chain Y/back-X weights, intra-line slack, carriage multiplier) with defaults matching old hard-coded behavior; threaded through ordering and collect_strokes_mm_for_page / G-code build (optional stroke_order_tuning on the API).

CLI & metrics

• samsung-notes metrics: per-page tables (--sweep-row-scale), sequential --optimize-row-scale [MIN:MAX:STEP] (default 0.8:2.5:0.1) for total pen-up mm across pages, plus 1D sweeps for order knobs: --optimize-x-gap-factor, --optimize-chain-y-weight, --optimize-chain-back-x-weight, --optimize-intra-line-y-factor, --optimize-carriage-y-lines (each optional MIN:MAX:STEP or built-in default when the flag is bare).
• pen_up_travel_xy_mm() — sum of Euclidean XY jumps between consecutive stroke starts (matches emitted G0 travel between polylines).
• --row-height-scale on gcode, inbox, and plot_strokes (--show-rows) so SVG row bands match the same grid as G-code when desired.

Docs

• README updated for metrics, tuning flags, and the single ordering story.

Suggested review focus

• Plot a sample .sdocx and compare visual row bands (plot_strokes --show-rows) vs pen-up from metrics when changing --row-height-scale.
• Confirm GRBL output still matches your machine profile (preamble/Z feeds unchanged in spirit; only stroke order and optional scale/tuning inputs are new).