Merge PR #692 from NikitkaRa: UI: Format Background picture fill sets transparency and tiling

# Conflicts:
#	crates/engine/src/cmd/design.rs
#	crates/ui-egui/src/panes.rs

docs/gaps.md

@@ -26,6 +26,7 @@
 > **Last reviewed:** 2026-10-14 · **Last updated:** 2026-10-14 · **Change:** minor (Slide Master Preserve and Title/Footers placeholders; checklist letters unchanged, breadth stays 79%, dialogs stay 27; previous: 3-D bevel, camera and face lighting rendered) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 > **Last reviewed:** 2026-10-14 · **Last updated:** 2026-10-14 · **Change:** minor (chart trendlines are drawn; previous: minor, chart trendlines round-trip; 3-D bevel, camera and face lighting rendered; IME composition and CJK interface text landed, #101; core-workflow alpha gate added; stage stays alpha; full re-measure against PowerPoint for Mac 16.113.4 and the open GitHub issues) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 > **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-11 · **Change:** minor (animated GIF export landed, #171; the video gap stays; previous: minor, core-workflow alpha gate added; stage stays alpha) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
+> **Last reviewed:** 2026-10-14 · **Last updated:** 2026-10-14 · **Change:** minor (Format Background picture options are pane controls, not a new dialog; dialogs stay 27; previous: 3-D bevel, camera and face lighting rendered) · **Target:** Microsoft PowerPoint for Mac 16.113 (Microsoft 365)
 
 Every known shortfall, one entry each, ranked by how much it stops someone who presents with
 PowerPoint from switching. This is the work list: pick from the top. Numbers are summarized in
@@ -357,6 +358,10 @@ Detail in [ui-parity.md](ui-parity.md).
   Action Settings, Print, Insert Object…). 8–14 h.
 - **Dialogs**: 30 dialogs vs PowerPoint's ~60 (Font, Find/Replace dialog, Replace Fonts, Print,
   Insert Object…). Size and Position, Bullets and Numbering, Action Settings and Date and Time are in. 8–14 h.
+- **Dialogs**: 27 dialogs vs PowerPoint's ~60 (Font, Bullets and Numbering, Find/Replace dialog,
+  Replace Fonts, Action Settings, Print, Insert Object…). Format Background picture options
+  (transparency, tile, offset, scale, alignment, mirror, and Apply to All copying a picture) are
+  pane controls on `design.background`, not another dialog. 8–14 h.
 - **Command palette defaults to an Export entry that fails** (#79). 0.5 h.
 
 ## Hardware
@@ -450,6 +455,7 @@ Detail in [localization-parity.md](localization-parity.md).
 | 2026-10-13 | trivial | Command palette skips commands that need a value, so Export opens the dialog (#79) |
 | 2026-10-14 | minor | Design ▸ Effects applies a named effect scheme. The checklist row stays P, so breadth stays 79%. Dialogs stay 27 |
 | 2026-10-14 | minor | Slide Master Preserve and Title/Footers placeholders. Checklist letters unchanged (breadth stays 79%); dialogs stay 27 |
+| 2026-10-14 | minor | Format Background picture and solid options are in the existing pane. Dialogs stay 27 |
 | 2026-10-13 | minor | Shape, picture and table rendering checked against PowerPoint on ~150 synthetic edge-case slides; 3-D bevels, cameras and face lighting now render approximately (gap narrowed to extrusion, rigs and the 3-D pane) |
 | 2026-10-13 | minor | Interactive decks: triggers, return-to-slide state and click rules landed in the slide show; the remaining pieces are one new entry under Features |
 | 2026-10-12 | minor | IME composition in slide text and notes, and CJK interface text with real glyphs (#101): the IME gap is now Korean on the web and table-cell underlines |