feat: slide panels, task calendar, team management, project editing, collapsible sections

- Add SlidePanel, TaskDetailPanel, PostDetailPanel, TeamPanel, TeamMemberPanel
- Add ProjectEditPanel, CollapsibleSection, DatePresetPicker, TaskCalendarView
- Update App, AuthContext, i18n (ar/en), PostProduction, ProjectDetail, Projects
- Update Settings, Tasks, Team pages
- Update InteractiveTimeline, MemberCard, ProjectCard, TaskCard components
- Update server API utilities
- Remove tracked server/node_modules (now properly gitignored)

client/src/components/SlidePanel.jsx

@@ -0,0 +1,19 @@
+import { createPortal } from 'react-dom'
+
+export default function SlidePanel({ onClose, maxWidth = '420px', header, children }) {
+  return createPortal(
+    <>
+      <div className="fixed inset-0 bg-black/20 z-[9998]" onClick={onClose} />
+      <div
+        className="fixed top-0 right-0 h-full w-full bg-white shadow-2xl z-[9998] flex flex-col animate-slide-in-right overflow-hidden"
+        style={{ maxWidth }}
+      >
+        {header}
+        <div className="flex-1 overflow-y-auto">
+          {children}
+        </div>
+      </div>
+    </>,
+    document.body
+  )
+}