feat: editor improvements and collapsible sidebars

Add collapse/expand toggle for the AppShell navigation sidebar and the
editor properties panel (both persisted to localStorage). Bundles other
in-progress editor work including position anchors, outlet sizing, PBR
textures, window slope/frame depth, curtain metadata, and various 2D/3D
rendering tweaks.

apps/server/prisma/migrations/20260408030305_add_window_slope_depth/migration.sql

@@ -0,0 +1,3 @@
+-- Add reveal (откос) depth to WallOpening. Existing rows default to 0
+-- (no visible slope), preserving prior render output for legacy windows.
+ALTER TABLE "WallOpening" ADD COLUMN "slopeDepth" REAL NOT NULL DEFAULT 0;