shoot_docs retakes 161 IDE pictures, and the help add-in's project file is published as a download

[KubaO]

Replaces the help add-in's screenshot tool with shoot_docs, which takes the IDE pictures across the documentation, and publishes the help add-in as a project file that includes the offline archive.

• docs: 158 IDE pictures retaken at 2x in the dark theme and shown at half size, and 3 new. IDE-FeatureMap (twelve labelled features) replaces the community screenshot and its copy, and the two LLVM JPGs become PNGs. Eight pictures are deleted: those four, three obsolete glyphs and one unreferenced picture. Static files fall from 258 to 253. Prose the new pictures contradict is corrected, in the WebView2 and CustomControls tutorials, Debug Console, New Project and Status Bar. Help Add-In (renamed from Documentation Help) offers the download first and the source route second.
• shoot_docs (new; replaces shoot_help_addin): takes the pictures from IDEs on private desktops, one per setup, with fixture projects under test/shots/. It draws the annotations (arrows, boxes, rings, labels, badges), composites and replicas of native select lists itself, and rewrites a picture only when its bytes differ. --jobs runs setups at once (a full run takes about 110 s) and --diffs writes difference pictures. WIP.Screenshots.md (new) has the plan.
• build: tbdocs packs add-in/ into tB/IDE/AddIns/downloads/tbDocsHelp.twinproj on every build, CI's included (addinProject task, about 28 MB): the files git tracks, the build's symbol index and its offline archive, so the add-in built from it needs no internet. The archive is now the build's helpArchive task. CI no longer passes --no-help-archive, and check_ci_workflows refuses it. The offline tree links to the file on the website. scripts/impexp.mjs is the one scripts/ module builder/ may import.
• help add-in: a 2 px line in the theme's text colour separates the results list from the page. In the detached window, whose frame blocks storage, the pages followed Windows' app mode instead of the IDE's theme and a link dropped the pane layout; both are now kept in window.name.
• tests: test/addin-project.test.mjs (new) is a test.bat and CI gate. The help lane checks the line and the window's theme in Light and Dark.

shoot_docs and the help lane need a twinBASIC install, so they stay outside every gate and CI. shoot_docs's command-line cases need none and run in test.bat.