feat: Implement end-to-end photo upload functionality

- Add file input with hidden native picker
- Convert selected images to base64 data URLs
- Validate file type (images only) and size (max 5MB)
- Display error alerts for invalid uploads
- Show preview immediately after selection
- Update help text to indicate camera button functionality
- Handle image load/error states properly

Now clicking the camera button opens file picker and uploads work fully.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

maternal-web/components/common/PhotoUpload.tsx

@@ -1,6 +1,6 @@
 'use client';
 
-import { useState } from 'react';
+import { useState, useRef } from 'react';
 import {
   Box,
   Avatar,
@@ -8,6 +8,7 @@ import {
   TextField,
   Typography,
   Paper,
+  Alert,
 } from '@mui/material';
 import { PhotoCamera, Person } from '@mui/icons-material';
 
@@ -27,6 +28,8 @@ export function PhotoUpload({
   size = 100
 }: PhotoUploadProps) {
   const [imageError, setImageError] = useState(false);
+  const [uploadError, setUploadError] = useState<string>('');
+  const fileInputRef = useRef<HTMLInputElement>(null);
 
   const handleImageError = () => {
     setImageError(true);
@@ -36,6 +39,46 @@ export function PhotoUpload({
     setImageError(false);
   };
 
+  const handleFileSelect = async (event: React.ChangeEvent<HTMLInputElement>) => {
+    const file = event.target.files?.[0];
+    if (!file) return;
+
+    // Validate file type
+    if (!file.type.startsWith('image/')) {
+      setUploadError('Please select an image file');
+      return;
+    }
+
+    // Validate file size (max 5MB)
+    const maxSize = 5 * 1024 * 1024; // 5MB
+    if (file.size > maxSize) {
+      setUploadError('Image size must be less than 5MB');
+      return;
+    }
+
+    // Convert to base64
+    const reader = new FileReader();
+    reader.onload = (e) => {
+      const base64String = e.target?.result as string;
+      onChange(base64String);
+      setUploadError('');
+      setImageError(false);
+    };
+    reader.onerror = () => {
+      setUploadError('Failed to read image file');
+    };
+    reader.readAsDataURL(file);
+
+    // Reset input
+    if (fileInputRef.current) {
+      fileInputRef.current.value = '';
+    }
+  };
+
+  const handleCameraClick = () => {
+    fileInputRef.current?.click();
+  };
+
   return (
     <Box sx={{ display: 'flex', flexDirection: 'column', gap: 2, alignItems: 'center' }}>
       <Paper
@@ -56,6 +99,12 @@ export function PhotoUpload({
           {label}
         </Typography>
 
+        {uploadError && (
+          <Alert severity="error" onClose={() => setUploadError('')} sx={{ width: '100%' }}>
+            {uploadError}
+          </Alert>
+        )}
+
         <Box sx={{ position: 'relative' }}>
           <Avatar
             src={!imageError && value ? value : undefined}
@@ -71,6 +120,15 @@ export function PhotoUpload({
             {!value || imageError ? <Person sx={{ fontSize: size / 2 }} /> : null}
           </Avatar>
 
+          <input
+            ref={fileInputRef}
+            type="file"
+            accept="image/*"
+            style={{ display: 'none' }}
+            onChange={handleFileSelect}
+            disabled={disabled}
+          />
+
           <IconButton
             sx={{
               position: 'absolute',
@@ -85,10 +143,7 @@ export function PhotoUpload({
             }}
             size="small"
             disabled={disabled}
-            onClick={() => {
-              // Future: Open file picker for actual upload
-              // For now, user can paste URL below
-            }}
+            onClick={handleCameraClick}
           >
             <PhotoCamera fontSize="small" />
           </IconButton>
@@ -102,7 +157,7 @@ export function PhotoUpload({
           size="small"
           placeholder="https://example.com/photo.jpg"
           disabled={disabled}
-          helperText="Paste an image URL or upload a photo"
+          helperText="Click camera to upload or paste an image URL"
         />
       </Paper>
     </Box>