feat(mentor-workspace): inline document preview matching applicant docs pattern

- Eye toggle expands the row below to embed FilePreview from
  @/components/shared/file-viewer (PDF iframe, image, video, Office docs)
- Download button uses explicit Content-Disposition: attachment via a
  new `disposition` input on workspaceGetFileDownloadUrl
- getPresignedUrl learns `inline: true` and optional `response-content-type`
  override so PDFs/images don't get force-downloaded by MinIO's default
- Eye button only renders for previewable mime types

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/minio.ts

@@ -78,13 +78,17 @@ export async function getPresignedUrl(
   objectKey: string,
   method: 'GET' | 'PUT' = 'GET',
   expirySeconds: number = 900, // 15 minutes default
-  options?: { downloadFileName?: string }
+  options?: { downloadFileName?: string; inline?: boolean; contentType?: string }
 ): Promise<string> {
   const publicClient = getPublicMinioClient()
   if (method === 'GET') {
-    const respHeaders = options?.downloadFileName
-      ? { 'response-content-disposition': `attachment; filename="${options.downloadFileName}"` }
-      : undefined
+    let respHeaders: Record<string, string> | undefined
+    if (options?.inline) {
+      respHeaders = { 'response-content-disposition': 'inline' }
+      if (options.contentType) respHeaders['response-content-type'] = options.contentType
+    } else if (options?.downloadFileName) {
+      respHeaders = { 'response-content-disposition': `attachment; filename="${options.downloadFileName}"` }
+    }
     return publicClient.presignedGetObject(bucket, objectKey, expirySeconds, respHeaders)
   } else {
     return publicClient.presignedPutObject(bucket, objectKey, expirySeconds)