Plan task P1.5. Modal canvas signature capture using HTML pointer events
+ Odoo Dialog service. Returns image/png dataURI via onSubmit callback;
caller decides what to do with it (e.g. /fp/workspace/sign_off attaches
to fp.job.step).
Canvas stays light even in dark mode for signature legibility.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
9d78bc4317
