feat: Loading States & Skeleton Screens - Issue #16

frontend/src/components/CalendarView.jsx

@@ -1,6 +1,7 @@
 import { useState, useEffect, useCallback } from 'react';
 import { useAuth } from '../context/AuthContext';
 import { TaskModal } from './TaskModal';
+import { SkeletonLoader } from './SkeletonLoader';
 import { toast } from 'react-toastify';
 
 const getWeekStart = (date = new Date()) => {

frontend/src/components/Dashboard.jsx

@@ -1,6 +1,7 @@
 import { useState, useEffect, useCallback } from 'react';
 import { useAuth } from '../context/AuthContext';
 import { TaskModal } from './TaskModal';
+import { SkeletonLoader } from './SkeletonLoader';
 import { toast } from 'react-toastify';
 
 const getWeekStart = (date = new Date()) => {
@@ -330,7 +331,7 @@ const Dashboard = () => {
 
       <div className="tasks-grid">
         {loading ? (
-          <div className="loading"><div className="spinner"></div></div>
+          <SkeletonLoader count={6} />
         ) : tasks.length === 0 ? (
           <div className="empty-state" style={{ gridColumn: '1 / -1' }}>
             <div className="empty-icon">📋</div>

frontend/src/components/MyTasks.jsx

@@ -1,6 +1,7 @@
 import { useState, useEffect, useCallback } from 'react';
 import { useAuth } from '../context/AuthContext';
 import { TaskModal } from './TaskModal';
+import { SkeletonLoader } from './SkeletonLoader';
 import { toast } from 'react-toastify';
 
 const getWeekStart = (date = new Date()) => {
@@ -176,7 +177,7 @@ const MyTasks = () => {
       </div>
 
       {loading ? (
-        <div className="loading"><div className="spinner"></div></div>
+        <SkeletonLoader count={6} />
       ) : filteredTasks.length === 0 ? (
         <div className="empty-state">
           <div className="empty-icon">📋</div>

frontend/src/components/SkeletonLoader.jsx

@@ -0,0 +1,99 @@
+export const SkeletonLoader = ({ count = 3 }) => {
+  return (
+    <>
+      {Array.from({ length: count }).map((_, i) => (
+        <div key={i} className="skeleton-card" style={{ 
+          padding: '20px', 
+          background: 'var(--bg-card)', 
+          borderRadius: '12px',
+          marginBottom: '12px',
+          animation: 'skeleton-pulse 1.5s ease-in-out infinite'
+        }}>
+          <div style={{ 
+            height: '20px', 
+            width: '60%', 
+            background: 'var(--bg-tertiary)', 
+            borderRadius: '4px',
+            marginBottom: '12px'
+          }} />
+          <div style={{ 
+            height: '14px', 
+            width: '80%', 
+            background: 'var(--bg-tertiary)', 
+            borderRadius: '4px',
+            marginBottom: '8px'
+          }} />
+          <div style={{ 
+            height: '14px', 
+            width: '40%', 
+            background: 'var(--bg-tertiary)', 
+            borderRadius: '4px'
+          }} />
+        </div>
+      ))}
+      <style>{`
+        @keyframes skeleton-pulse {
+          0%, 100% { opacity: 1; }
+          50% { opacity: 0.5; }
+        }
+      `}</style>
+    </>
+  );
+};
+
+export const SkeletonTable = ({ rows = 5, cols = 4 }) => {
+  return (
+    <div style={{ padding: '20px', background: 'var(--bg-card)', borderRadius: '12px' }}>
+      <div style={{ display: 'flex', gap: '16px', marginBottom: '16px' }}>
+        {Array.from({ length: cols }).map((_, i) => (
+          <div key={i} style={{ 
+            height: '16px', 
+            flex: 1, 
+            background: 'var(--bg-tertiary)', 
+            borderRadius: '4px'
+          }} />
+        ))}
+      </div>
+      {Array.from({ length: rows }).map((_, rowIdx) => (
+        <div key={rowIdx} style={{ display: 'flex', gap: '16px', marginBottom: '12px' }}>
+          {Array.from({ length: cols }).map((_, colIdx) => (
+            <div key={colIdx} style={{ 
+              height: '14px', 
+              flex: 1, 
+              background: 'var(--bg-tertiary)', 
+              borderRadius: '4px',
+              opacity: 1 - (rowIdx * 0.1)
+            }} />
+          ))}
+        </div>
+      ))}
+      <style>{`
+        @keyframes skeleton-pulse {
+          0%, 100% { opacity: 1; }
+          50% { opacity: 0.5; }
+        }
+      `}</style>
+    </div>
+  );
+};
+
+export const LoadingSpinner = ({ size = 'medium' }) => {
+  const sizes = { small: '20px', medium: '40px', large: '60px' };
+  return (
+    <div className="loading-spinner" style={{ 
+      width: sizes[size], 
+      height: sizes[size],
+      border: '3px solid var(--bg-tertiary)',
+      borderTop: '3px solid var(--accent-primary)',
+      borderRadius: '50%',
+      animation: 'spin 1s linear infinite'
+    }}>
+      <style>{`
+        @keyframes spin {
+          0% { transform: rotate(0deg); }
+          100% { transform: rotate(360deg); }
+        }
+      `}</style>
+    </div>
+  );
+};

frontend/src/index.css

@@ -51,6 +51,21 @@
   box-sizing: border-box;
 }
 
+@keyframes skeleton-pulse {
+  0%, 100% { opacity: 1; }
+  50% { opacity: 0.5; }
+}
+
+@keyframes spin {
+  0% { transform: rotate(0deg); }
+  100% { transform: rotate(360deg); }
+}
+
+@keyframes fadeIn {
+  from { opacity: 0; transform: translateY(10px); }
+  to { opacity: 1; transform: translateY(0); }
+}
+
 body {
   font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
   background: var(--bg-primary);