A Line, Circle, PSet, Scale page, WARNINGs for known defects, and bug reproducers with pictures

[KubaO]

Adds a Core page on the drawing syntax, turns known silent and crashing twinBASIC defects into WARNINGs, and lets a bug reproducer carry pictures and a VB6 form.

• docs: Line, Circle, PSet, Scale (new; 921 to 922 pages) explains how the drawing syntax becomes a call with a flags argument, how a colour value is read, and what the built-in surfaces do with the flags, with VB6's differences. The six drawing surfaces link to it and gain the Circle angle rules; Point says it returns 0 and warns TB0009; a bare Scale resets to twips. Two samples draw on a form and read the pixel back, checked on BETA 995 and in VB6.
• docs, corrections: LSet pads since BETA 984, RSet drops the rightmost characters, StrConv states its LCID and vbProperCase rules, and TextBox raises Change once per Text assignment. --buildAndExit32 exits 0 only for an error in code nothing calls, and hangs for one the build reaches.
• docs, rule: a known defect that silently gives a wrong result, crashes, or hides a silent part behind an error is a WARNING until a fixed build ships (WIP.md, Authoring.md). 34 pages carry one. The most common is a colour property that stores a non-colour (23 pages; VB6 raises 380); the others are system colours, Circle angles, TextBox.Text, LSet, RSet, StrConv, Err.Raise and four COM interfaces.
• bugs: 13 new entries, each with a reproducer: colour values, LSet, RSet and StrConv, TextBox.Text, Circle angles, and five defects of the debugger and Debug Console. 58 reproducers become 71 (32 filed, 39 queued); the Circle one is filed as Circle with a positive angle above 2 pi raises no error and draws an arc, where VB6 raises error 5 twinbasic#2463. Eight of the new ones have a VB6 project.
• bug_repro:
  • Pictures for graphical defects: new --with-images adds PngDump modules for twinBASIC and VB6; run and vb6 keep what they draw as images/<name>-tb.png and -vb6.png, plus a -compare.png of both and their difference; expect.imagesDiffer lets verify judge it. scripts/lib/png.mjs (new) reads, writes and compares the PNG files.
  • vb6 builds a project with a form or a user control, which VB6 refuses under Unattended Execution, and runs every exe on a private desktop.
  • cli mode runs each compiler command on a private desktop and closes the dialog boxes it opens; damaged-project-modal-box becomes a cli reproducer over its four damaged inputs. tb-launch.ps1 travels in TBBUILD_SCRIPT, because -EncodedCommand overflowed the command line past about 12,000 characters.
• check_examples, vb6run: a form template with a real, empty Form1 for check_run samples that draw on a form; the dispatcher unloads each form a sample leaves loaded. vb6run --docs builds them in VB6 with a blank Form1.frm.
• ide-test, addin-test: ide-test.bat gains five lanes, one per debugger and Debug Console entry (4 to 9). addin-test.bat gains the env lane, which holds that TB_ADDIN_TEST reaches an add-in in the compiler and after a restart (11 lanes, under two minutes on BETA 995).

bug_repro's pictures and cli mode, vb6run, ide-test.bat and addin-test.bat need a twinBASIC install or VB6, so they stay outside every gate and CI, like examples.bat. test/png.test.mjs needs neither and runs in test.bat and CI.