feat: parse CSS contain values in geometry normalization

- Add CONTAIN_MAP with bitfield flags matching CDP extractor schema
  (layout=1, paint=2, size=4, style=8, strict=15, content=7, inline-size=16)
- Parse space-separated contain keywords in normalizeStyles()
- Replace containFlags[i]=0 TODO with actual value lookup
- Unknown contain keywords map to 0 gracefully

packages/imhotep-geometry/src/normalize.ts

@@ -322,6 +322,16 @@ const VISIBILITY_MAP: Record<string, VisibilityValue> = {
   collapse: VisibilityValue.Collapse,
 }
 
+const CONTAIN_MAP: Record<string, number> = {
+  none: 0,
+  layout: 1,
+  paint: 2,
+  size: 4,
+  style: 8,
+  strict: 15,
+  content: 7,
+  'inline-size': 16,
+}
 const CLIP_KIND_MAP: Record<string, ClipKind> = {
   overflow: ClipKind.Overflow,
   clipPath: ClipKind.ClipPath,
@@ -648,7 +658,11 @@ export function normalizeStyles(raw: RawStyle[], strings: StringTable): Styles {
     overflowY[i] = OVERFLOW_MAP[s.overflowY] ?? OverflowValue.Visible
     opacity[i] = s.opacity
     visibility[i] = VISIBILITY_MAP[s.visibility] ?? VisibilityValue.Visible
-    containFlags[i] = 0 // TODO: parse contain values
+    if (s.contain) {
+      for (const part of s.contain.split(/\s+/)) {
+        containFlags[i] |= CONTAIN_MAP[part.toLowerCase()] ?? 0
+      }
+    }
     pointerEvents[i] = internString(strings, s.pointerEvents)
     lineHeight[i] = s.lineHeight
     fontFamilyStringId[i] = internString(strings, s.fontFamily)