fix(tui): restore hidden session scrollbar default (#20947)

Author: kitlangton

packages/opencode/src/cli/cmd/tui/routes/session/index.tsx

@@ -155,7 +155,7 @@ export function Session() {
   const [timestamps, setTimestamps] = kv.signal<"hide" | "show">("timestamps", "hide")
   const [showDetails, setShowDetails] = kv.signal("tool_details_visibility", true)
   const [showAssistantMetadata, setShowAssistantMetadata] = kv.signal("assistant_metadata_visibility", true)
-  const [showScrollbar, setShowScrollbar] = kv.signal("scrollbar_visible", true)
+  const [showScrollbar, setShowScrollbar] = kv.signal("scrollbar_visible", false)
   const [diffWrapMode] = kv.signal<"word" | "none">("diff_wrap_mode", "word")
   const [animationsEnabled, setAnimationsEnabled] = kv.signal("animations_enabled", true)
   const [showGenericToolOutput, setShowGenericToolOutput] = kv.signal("generic_tool_output_visibility", false)