feat(feed): 피드 크기 계산 계약을 추가한다

app/src/main/java/kr/co/vividnext/sodalive/v2/widget/feed/FeedContentImageSize.kt

@@ -0,0 +1,14 @@
+package kr.co.vividnext.sodalive.v2.widget.feed
+
+data class FeedContentImageSize(
+    val widthDp: Int,
+    val heightDp: Int
+) {
+    companion object {
+        fun from(widthDp: Int, category: FeedContentCategory): FeedContentImageSize {
+            require(widthDp > 0) { "widthDp must be greater than 0." }
+            val height = (widthDp * category.ratioHeight.toFloat() / category.ratioWidth).toInt()
+            return FeedContentImageSize(widthDp = widthDp, heightDp = height)
+        }
+    }
+}

app/src/main/java/kr/co/vividnext/sodalive/v2/widget/feed/FeedSize.kt

@@ -0,0 +1,27 @@
+package kr.co.vividnext.sodalive.v2.widget.feed
+
+data class FeedSize(
+    val rootWidthDp: Int
+) {
+    companion object {
+        private const val FIGMA_ROOT_WIDTH_DP = 374
+
+        fun from(
+            variant: FeedVariant,
+            widthMode: FeedWidthMode,
+            parentAvailableWidthDp: Int,
+            horizontalItemDecorationDp: Int = 0
+        ): FeedSize {
+            val width = when (widthMode) {
+                FeedWidthMode.FigmaFixed -> FIGMA_ROOT_WIDTH_DP
+                FeedWidthMode.ParentAvailable -> {
+                    require(parentAvailableWidthDp > 0) { "parentAvailableWidthDp must be greater than 0." }
+                    require(horizontalItemDecorationDp >= 0) { "horizontalItemDecorationDp must be 0 or greater." }
+                    parentAvailableWidthDp - horizontalItemDecorationDp
+                }
+            }
+            require(width > 0) { "rootWidthDp must be greater than 0." }
+            return FeedSize(rootWidthDp = width)
+        }
+    }
+}

app/src/main/java/kr/co/vividnext/sodalive/v2/widget/feed/FeedWidthMode.kt

@@ -0,0 +1,6 @@
+package kr.co.vividnext.sodalive.v2.widget.feed
+
+enum class FeedWidthMode {
+    FigmaFixed,
+    ParentAvailable
+}