chore: upgrade postcss to ^8.5.25 to address CVE-2026-69153

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: claude[bot]

yarn.lock

@@ -19680,13 +19680,13 @@ __metadata:
   linkType: hard
 
 "postcss@npm:^8.4.47, postcss@npm:^8.5.12, postcss@npm:^8.5.15":
-  version: 8.5.22
-  resolution: "postcss@npm:8.5.22"
+  version: 8.5.25
+  resolution: "postcss@npm:8.5.25"
   dependencies:
     nanoid: "npm:^3.3.16"
     picocolors: "npm:^1.1.1"
     source-map-js: "npm:^1.2.1"
-  checksum: 10c0/9e143ee457988049d5f187116fd37f2750ae9d8d71cc99eae690b776e549e134b34086cbaa2f0360ecd1729b15d918227bd0fc3a2ffbe341f7212d0827080793
+  checksum: 10c0/0a12c1e74b456c57122e81f684e02fd98ff4d57526f794d10c996df1147158808f5ae373ac82b988c8de6cbbaa82dbd7b13803b14f5dd3cf7cc6a42ccad5c9f2
   languageName: node
   linkType: hard