FX.139 Screenshot mode for /lab: ?shot=1 hides the Lab badge, stamp and staff panel; capture tools shoot from /lab

Why: 0.9 media (store shots, tutorial pictures, About/README screenshots, videos) should not wait for the real 0.9 builds, and the lab badge, build stamp, staff panel and 'a Discord member' must never show in them. Changed: shot_mode()/shot_version() in core/functions/helpers.php (lab testers only, /lab/ pages only, per request: no cookie or session, so it cannot reach /use). With ?shot=1 the app bar drops the Lab badge, build stamp and version list; Settings > Version and the About dialog show the release number (0.9, or ?shotv=); header.inc drops the staff panel. New tools/shot-target.mjs (LAB_SHOT=1 points tools/help-walkthrough-shots.mjs, tools/help-shots.mjs and videos/kit/shoot.mjs at /lab/<app>?shot=1 as the shell test admin); stores/kit/lab-shots.mjs now uses the param (its visible-text guard stays); tools/shot-freeze.php record|check lists apps whose lab build moved since the shots (docs/0.9-shots-freeze.json). Tried: lab-shots (CadCraft, BimCraft) and help-shots (MarkupCraft) on the VPS, badge and staff panel gone, guard passed. Untested: the tutorial walkthrough and video tools with LAB_SHOT=1 end to end, native window chrome per OS (needs a real Studio build), no freeze recorded yet.