v0.2.7 — crash-proof entry, editable parameters, width card

V-bit day: a snapped tip turned into three fixes.

Crash-proof cut entry

A V-bit died at first plunge because the approach rapid stopped only 0.2 mm above the believed surface — any Z-zero error (classic after a bit change) buried the tip at rapid speed. Now:

• The rapid stops 0.5 mm up; the final approach descends as a feed move at plunge feed. A Z error costs a scrapped line, not a tool.
• The ramp lead-in also runs at plunge feed instead of XY feed (steep-descent detection — leveling's gentle warps stay at full speed).

Job parameters in the UI

The cut-parameter forms (bit, depths, feeds, V-bit tip/angle/target width) were preset-only. New Job parameters group on the Setup page — click Edit values for live Traces/Drill/Cutout tabs. Edits update the preview immediately; Save... keeps them as your preset.

V-bit width test card

Sub-0.1 mm line widths can't be measured with calipers. New coupon at examples/vbit_width: 8 tracks stepping 0.40 → 0.05 mm design width, each with its own probe-pad pair — the narrowest track that still beeps on a multimeter brackets the actual cut width to 50 µm. Reading table in the folder's README.

468 automated tests.