Designer: deal the section settings out into four tabs

[ZombieHDGaming]

What this changes

The designer's middle pane was one column of fifteen groups — the content rows, the type's own settings, the placement rows, up to five StyleEditors, eight background slots, and a table — all stacked in a pane a third of a window wide. Folding the groups away made the column shorter without making it any less of a column: somebody working on the words of a list still scrolled past the geometry and the styles to reach the entry table.

The settings are now dealt out into four tabs (EditorTab):

Tab	Holds
Content	Content Properties (text, subtitle, logo, playback), the entry table, the divider's three piece stacks
Layout	the type's own settings (%1 Settings) and Placement on the Canvas
Style	the primary, secondary, bridge and two row-subtitle style editors
Background	the eight background slot groups

Nothing about the document changes — a tab is where a control is drawn and nothing else. Section types, persistence and the visibility rules are untouched.

The header stays above the tabs

The type picker with its switches and help line, the label field, the visible box and the Show every setting switch sit above the tab strip. They aren't settings of any one job: the type decides what every tab holds, the label is how a section is found again in the list, and the advanced switch reaches rows on three of the four pages. Leaving the tab you're working in to flip one of them would lose your place to change something that governs all of them.

Scrolling moved inside

Each tab page has its own QScrollArea, so the header and the tab strip can't be scrolled off the top and each page keeps the place it was left at. DesignerDialog therefore adds the editor straight to the splitter instead of wrapping it in a scroll area of its own (editorScroll is gone; editor takes its place in the two spots that used it).

Empty tabs go away

A Spacer has no words, no styles and no panels, so three of the four would be empty panes inviting the reader to look for settings that aren't there. refreshTabVisibility asks the groups on each page rather than re-deriving from the section type, so it can't disagree with the visibility pass that has just run; it uses isHidden rather than isVisible because the page of an unselected tab is itself hidden. The chosen tab is remembered rather than forced — a tab going away under the reader takes the selection with it, and desiredTab puts them back on it once the next section has one again, with restoringTab keeping that shuffle from being read as a choice.

Other changes

• Designer.Group.Placement renamed from "Layout Properties" to "Placement on the Canvas" — "Layout ▸ Layout Properties" read as a stutter. Say the word and I'll put it back.
• Four new locale keys: Designer.Tab.{Content,Layout,Style,Background}.
• ARCHITECTURE.md's designer section rewritten to describe the tabs, the pinned header, the per-page scrolling and the empty-tab rule.

Verification

The plugin's own UI isn't covered by tests/ (the harness compiles model/, render/ and util/ without Qt Widgets), so this was checked two ways:

• Existing suite: cmake -S . -B build -DENABLE_TESTS=ON && ctest — passes, 0 failures.
• Offscreen harness built for this change (throwaway, not committed): links SectionEditor and its dependencies against a stubbed locale table, drives a section of each type through it and reads the tab bar back.

Title -> Content*, Layout, Style, Background
TextList -> Content*, Layout, Style, Background
Bridged -> Content*, Layout, Style, Background
SectionDivider -> Content*, Layout, Style, Background
Spacer -> Layout*, Background
StickyBlock -> Layout*, Background
picked Style on Title -> Content, Layout, Style*, Background
then Spacer -> Layout, Background*
then Title again -> Content, Layout, Style*, Background
round trip: label=Cast paddingTop=42 size=77 entries=2 type=same

Rendered grabs confirm the pinned header sits above the strip, each page's first group starts at the top of its own scroll area, and a list's Content tab is now the entry table filling the pane rather than a table below fifteen groups.

clang-format 19.1.1 reports no diffs on the four touched source files.

🤖 Generated with Claude Code

https://claude.ai/code/session_019UvPd5wu54qwoNAHqN9U8o

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Generated by Claude Code