Make TopBar title input fill available space

Replace fixed minWidth with flex: 1 so the title input expands
to use all remaining space in the left section.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: kube

libs/@hashintel/petrinaut/src/views/Editor/components/TopBar/floating-title.tsx

@@ -4,13 +4,15 @@ const floatingTitleInputStyle = css({
   fontSize: "sm",
   fontWeight: "medium",
   color: "neutral.s120",
-  minWidth: "[200px]",
+  flex: "1",
+  minWidth: "0",
   borderRadius: "sm",
-  padding: "[4px 8px]",
+  px: "2",
+  py: "1",
   _focus: {
     outline: "2px solid",
     outlineColor: "blue.s60",
-    outlineOffset: "[0px]",
+    outlineOffset: "0",
   },
   _placeholder: {
     color: "neutral.s100",