ui: Mass layout refactor

- Replaced TabWidget mode selection with ComboBox
- Moved Timeline out of record/review widgets
- Added TimelineState struct
- Set slint style to cosmic

ui/global.slint

@@ -0,0 +1,21 @@
+export global TimeString {
+    pure function pad-mh(seconds: int, param: int) -> string {
+        if seconds / param < 10 {
+            return "0\{floor(seconds / param)}";
+        }
+        return "\{floor(seconds / param)}";
+    }
+    pure function pad-s(seconds: int) -> string {
+        if mod(seconds, 60) < 10 {
+            return "0\{mod(seconds, 60)}";
+        }
+        return "\{mod(seconds, 60)}";
+    }
+    public pure function from(seconds: int) -> string {
+        return "\{pad-mh(seconds, 3600)}:\{pad-mh(mod(seconds, 3600), 60)}:\{pad-s(seconds)}";
+    }
+}
+
+export global Const {
+    out property <int> max-offset: 24 * 3600 - 1;
+}