feat(note): add image upload functionality for notes

- Implemented a new endpoint in the Note controller to handle image uploads associated with notes.
- Added the `uploadImage` method in NoteService to manage image storage and return public URLs.
- Updated API routes to include the new image upload endpoint, enhancing note management capabilities.

app/note/service/NoteService.php

@@ -268,6 +268,33 @@ class NoteService
         return $this->formatAudio($audio);
     }
 
+    /**
+     * 上传笔记图片。
+     *
+     * 这里不额外建表，直接返回公开图片地址，由前端把图片标记写回 note.content，
+     * 以便在跨设备打开同一笔记时仍能恢复图片内容。
+     *
+     * @param int $noteUserId
+     * @param int $id
+     * @param File $file
+     * @return array
+     * @throws \Exception
+     */
+    public function uploadImage(int $noteUserId, int $id, File $file): array
+    {
+        $this->getOwnedNote($noteUserId, $id);
+        $savedPath = str_replace('\\', '/', Filesystem::disk('public')->putFile('note/image', $file));
+
+        return [
+            'disk' => 'public',
+            'file_path' => $savedPath,
+            'image_url' => $this->buildPublicFileUrl($savedPath),
+            'file_size' => (int) $file->getSize(),
+            'mime_type' => $this->detectImageMimeType($savedPath, $file),
+            'updated_at' => time(),
+        ];
+    }
+
     /**
      * 创建分享
      *
@@ -444,6 +471,38 @@ class NoteService
         return $mimeMap[$extension] ?? 'application/octet-stream';
     }
 
+    /**
+     * 推断图片 MIME。
+     *
+     * 与音频上传一样，这里优先按扩展名兜底，避免依赖 fileinfo 扩展。
+     *
+     * @param string $savedPath
+     * @param File $file
+     * @return string
+     */
+    private function detectImageMimeType(string $savedPath, File $file): string
+    {
+        $extension = strtolower((string) pathinfo($savedPath, PATHINFO_EXTENSION));
+        if ($extension === '') {
+            $extension = strtolower((string) pathinfo((string) $file->getOriginalName(), PATHINFO_EXTENSION));
+        }
+
+        $mimeMap = [
+            'avif' => 'image/avif',
+            'bmp' => 'image/bmp',
+            'gif' => 'image/gif',
+            'heic' => 'image/heic',
+            'heif' => 'image/heif',
+            'jpeg' => 'image/jpeg',
+            'jpg' => 'image/jpeg',
+            'png' => 'image/png',
+            'svg' => 'image/svg+xml',
+            'webp' => 'image/webp',
+        ];
+
+        return $mimeMap[$extension] ?? 'application/octet-stream';
+    }
+
     /**
      * 规范化标题
      *