feat: web automation wrapper (#1349), DATALINK table on web, System theme; honest decode accounting

Ported from 2c38de53 (#1717). Main already carries the hatch PDF draw
order fix (#1345), the numeric set_properties compare (#1348) and the
web open from bytes, so those parts stay out; what remains:

#1349 — window.ocsControl.ready/request promise wrapper with an
ocs-ready event (web/ocs-control.js, loaded by the web page), and the
startup donation prompt is suppressed once a control request is seen
(opt-in pre-boot via localStorage["opencadstudio.automation"] = "1").
docs/automation/web.md documents both. The control protocol stays at 1.

DATALINK CSV-to-table works on web (picker + bytes through the session
registry — was std::fs, silently dead); COLORSCHEME accepts System
(prefers-color-scheme on web, AppsUseLightTheme on Windows).

Decode accounting, made honest per the fix-of-fix review: into_rgba8
allocates the RGBA destination while the native buffer is alive for
every non-Rgba8 layout (L8 5, La8 6, Rgb8 7, L16 6, La16 8 B/px
peaks — the formula now says so), GIF bills the screen+frame
coexistence at 8 B/px, and TIFF drops the 3x multipliers both ways —
tiff 0.11 splits the given budget between frame and scratch (a total
ceiling), so the old double-billing refused honest 16-bit GeoTIFFs
~2.25x early while admitting hostile chunk transients at 3x.

(cherry picked from commit 2c38de53)

locales/ru-RU/opencadstudio.ftl

@@ -4412,6 +4412,7 @@ layout =
     .vplayer-f-layer-freeze-t-layer-thaw-enter-exit = VPLAYER F <слой> = заморозить | T <слой> = разморозить | Enter = выход
 
 view =
+    .color-scheme-set-to-system-currently-name = Цветовая схема установлена на «Системную» (сейчас __ocs_fmt_0__).
     .ss-create-sheet-set = Create Sheet Set
     .ss-requires-integer-between = Требуется целое число от __ocs_fmt_0__ до __ocs_fmt_1__.
     .ss-new-sheet = New Sheet