Redesign routines UI to match issue page design language

- Remove Card wrappers and gray backgrounds from routine detail
- Use max-w-2xl container layout like issue detail page
- Add icons to tabs (Clock, Play, ListTree, Activity) matching issue tabs
- Make activity tab compact (single-line items with space-y-1.5)
- Create shared RunButton and PauseResumeButton components
- Build user-friendly ScheduleEditor with presets (hourly, daily, weekdays, weekly, monthly)
- Auto-detect timezone via Intl API instead of manual timezone input
- Use shared action buttons in both AgentDetail and RoutineDetail
- Replace bordered run history cards with compact divided list

Co-Authored-By: Paperclip <noreply@paperclip.ing>

ui/src/components/AgentActionButtons.tsx

@@ -0,0 +1,51 @@
+import { Pause, Play } from "lucide-react";
+import { Button } from "@/components/ui/button";
+
+export function RunButton({
+  onClick,
+  disabled,
+  label = "Run now",
+  size = "sm",
+}: {
+  onClick: () => void;
+  disabled?: boolean;
+  label?: string;
+  size?: "sm" | "default";
+}) {
+  return (
+    <Button variant="outline" size={size} onClick={onClick} disabled={disabled}>
+      <Play className="h-3.5 w-3.5 sm:mr-1" />
+      <span className="hidden sm:inline">{label}</span>
+    </Button>
+  );
+}
+
+export function PauseResumeButton({
+  isPaused,
+  onPause,
+  onResume,
+  disabled,
+  size = "sm",
+}: {
+  isPaused: boolean;
+  onPause: () => void;
+  onResume: () => void;
+  disabled?: boolean;
+  size?: "sm" | "default";
+}) {
+  if (isPaused) {
+    return (
+      <Button variant="outline" size={size} onClick={onResume} disabled={disabled}>
+        <Play className="h-3.5 w-3.5 sm:mr-1" />
+        <span className="hidden sm:inline">Resume</span>
+      </Button>
+    );
+  }
+
+  return (
+    <Button variant="outline" size={size} onClick={onPause} disabled={disabled}>
+      <Pause className="h-3.5 w-3.5 sm:mr-1" />
+      <span className="hidden sm:inline">Pause</span>
+    </Button>
+  );
+}