[SeoJCalive]

What does this change?

Part of #806. This changes the default slots of all 19 built-in donuts to the table agreed in the issue:

• range (b), core + stage 1, every face 8 slots or fewer: [Feature]: A rule for what Filee shows by default, before more formats are added #806 (comment)
• the re-picked back faces: [Feature]: A rule for what Filee shows by default, before more formats are added #806 (comment)
• the final answer: [Feature]: A rule for what Filee shows by default, before more formats are added #806 (comment)

Only new installs and Reset library / Reset donut get the new layout. An existing user's donuts don't change, and neither does anything migrated or imported from an older version.

The new layout

Donut	Front	Back
Images	6	8
PDF	7	8
Documents	7	3
Spreadsheets	6	5
Presentations	7	4
HWP / HWPX	7	4
Text	6	4
E-books	6	2
Video	6	8
Audio	5	5
Subtitles	2	1
Vector	5	5
Archives	4	0
CAD	5	3
Fonts	4	1
Data	5	4
3D models	5	1
GIS	5	1
Mixed	5	2

How each face was built:

• Front faces: core + stage-1 slots, in the order of the posted table. GIF is a core slot on the image front, right after WEBP.
• Back faces of donuts with editing tools (images, PDF, video, audio): the edit slots, then metadata removal where there's room, then the conversions re-picked in the second comment, then "ZIP one". Metadata removal is on video, audio and PDF (in place of ODT). Images have no room for it.
• Back faces of the other donuts: stage-1 and stage-2 slots in their current order. Mixed keeps JPG and DOCX.
• New slots: none outside the two decided ones, GIF on images and metadata removal on video/audio. No new presets or groups. Every removed slot stays in the preset library, so users can put it back in the toolbar editor.

Type of change

• New feature or improvement

Existing users

Saved profiles are never compared with the defaults when they're read, so a user's own donuts can't change. What could leak the new layout into old data were the migrations that copy the current defaults:

• AddBackFaces, for profiles saved without back faces (before schema 30, or in a bundle);
• AddPdfSlides (schema < 18);
• the migrations that add a donut that didn't exist yet (v4, v5, GIS, data, subtitles, 3D models, catalog);
• re-adding the mixed donut when every mixed donut was deleted.

These now read a frozen copy of the previous defaults, BuiltInData schema-58 profiles, which is identical to CreateProfiles() at 51a6ba2. PdfDonut keeps the schema-18–58 PDF front for AddPdfSlides. New installs, ResetLibrary and ResetProfile use the new CreateProfiles(). The schema version doesn't change, because the file format and existing data are the same.

How "unchanged" is judged: for each case the new code's result is compared with a fixture captured by running the old code (51a6ba2) on the same input. The fixtures were not derived from the new code. Each comparison covers:

• every donut's front and back slot ids and their order;
• the order of the donut list;
• extensions;
• user-edited preset options and names.

The cases are Load and Import of:

• the old defaults;
• an edited layout;
• a schema-17 PDF front;
• a default donut without a back face;
• a user donut without a back face;
• schema-29 data.

How was it tested?

• dotnet format --verify-no-changes
• dotnet test. On Linux I ran Core (900/900) and the App tests for the toolbar, profiles, presets, DefaultPlacementTests and RenderTests (371/372). I didn't run the whole App suite locally; CI covers it.
  • The one failure is RenderTests.Engines_page_shows_versions_descriptions_and_download_speed. The system Ghostscript and LibreOffice on that machine report an empty version. This PR doesn't touch engines or the engines page.
• DefaultPlacementTests (as asked): 8/8 pass, no violations, no generic-only slots.
• Tried it in the app: before/after screenshots of every donut face are below.

Mutation checks. Each change was applied on its own, then reverted:

Change	Result
Load/Import overwrite profiles with the new CreateProfiles()	the 11 old-vs-new comparisons fail
AddBackFaces uses the new defaults	the 5 comparisons that need it fail
Remove to-png from the frozen image front	the frozen-baseline test fails

Screenshots (UI changes)

Each image shows before on the left and after on the right, rendered by the same headless render test on 51a6ba2 and on this branch. Greyed slots are tools whose engine isn't installed on the capture machine (FFmpeg, Calibre), the same before and after.

The other 22 faces that changed

The 7 faces not shown are unchanged: presentations, CAD and mixed fronts; subtitles, fonts, data and GIS backs. The archives back has no slots before or after.

Checklist

• New UI strings are in all src/Filee.App/Assets/i18n/*.json files (none added)
• New third-party code or binaries are listed in THIRD-PARTY-NOTICES.md (none added)
• The PR does one thing (unrelated changes go in a separate PR)