Room levels 2 and 3, researched in the library: a quarter better each, brighter, with gold trim

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

lang/en.lang

@@ -939,6 +939,7 @@ research.now = Researching: {0} ({1}%)
 research.next = then: {0}
 research.done = Nothing left to research here.
 msg.researched = Researched: {0}! It is in the build menu now.
+msg.room_upgraded = Research: {0} reaches level {1} – it works a quarter better, and it shows.
 msg.tool_research = Not researched yet - creatures studying in the library work on it.
 
 msg.script = {0}