feat(inventory-list-display): icon_atlas override + fit-to-bounds rendering

Two consumer-side fixes for ADR-0054 §3 (Item-Visual-Identity).

1) default_icon_resolver tries icon_atlas + icon_uv.* first; falls
   back to sprite_atlas + sprite_uv.* when the override is absent.
   Items inherit their world-render sprite as the UI icon for free
   (TC_Basics-style object sprites work directly as icons); dedicated
   low-res UI-icons can later land via icon_atlas without API churn.

2) Render path scales the icon uniformly to fit a (row_height - 4)
   box, centered. The world-sprite-as-icon path (300×300 native) no
   longer overflows the row; pre-baked small icons stay sharp because
   the scale is applied around the visual center of the UV rect, not
   the texture origin.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

init.lua

@@ -54,9 +54,26 @@ local M = {}
 -- -----------------------------------------------------------------------
 
 -- default_icon_resolver(item) -> icon_table or nil
--- Reads sprite_atlas + sprite_uv.* from item properties.
--- Returns nil if sprite_atlas is not set (no icon for this item).
+-- v0.2.0: per ADR-0054 §3 — additive UI-icon override on top of the
+-- world-sprite. If the item declares `icon_atlas` (string) + `icon_uv.*`
+-- (numbers), use those (e.g. for dedicated low-res UI icons baked
+-- separately). Otherwise fall back to `sprite_atlas` + `sprite_uv.*`
+-- (the world-render sprite, which today doubles as the UI icon for
+-- TC_Basics-style item-shaped sprites).
+-- Returns nil if neither chain yields a sprite (no icon for this item).
 local function default_icon_resolver(item)
+    local icon_atlas = item:get_property("icon_atlas")
+    if icon_atlas and icon_atlas ~= "" then
+        return {
+            atlas = icon_atlas,
+            uv = {
+                x = item:get_property("icon_uv.x"),
+                y = item:get_property("icon_uv.y"),
+                w = item:get_property("icon_uv.w"),
+                h = item:get_property("icon_uv.h"),
+            },
+        }
+    end
     local atlas = item:get_property("sprite_atlas")
     if not atlas or atlas == "" then return nil end
     return {
@@ -108,13 +125,21 @@ local function render_widget(widget_def, ctx)
                                   widget_def.widget_id, icon.atlas)
             if ok and tex then
                 local uv = icon.uv
-                -- draw_sprite_transform(tex, x, y, rot, scl_x, scl_y,
-                --   origin_x, origin_y, tint, u, v, uw, vh)
-                -- rot=0, scl=1, origin at top-left (0,0), tint=white
+                -- v0.2.0: fit-to-bounds. Compute uniform scale so the
+                -- larger UV dimension matches the icon box (row_height
+                -- minus a small margin), then center-anchor inside the
+                -- box. Lets world-sprites (e.g. TC_Basics 300×300 native)
+                -- and pre-baked icons share the same row layout without
+                -- per-item magic numbers.
+                local box     = ctx.theme.row_height - 4
+                local max_uv  = (uv.w > uv.h) and uv.w or uv.h
+                local s       = box / max_uv
+                local draw_x  = ctx.bounds.x + (box - uv.w * s) / 2
+                local draw_y  = row_y + 2 + (box - uv.h * s) / 2
                 engine.render.draw_sprite_transform(
                     tex,
-                    ctx.bounds.x, row_y,
-                    0, 1, 1,
+                    draw_x, draw_y,
+                    0, s, s,
                     0, 0,
                     0xFFFFFFFF,
                     uv.x, uv.y, uv.w, uv.h)