You are a Senior Frontend Engineer.

Project:
Training Management System (TMS)

Current task:
Improve certificate attachment display fallback.

Requirement:
In the certificate column/card, show a certificate icon placeholder when there is no image preview. If there is no attached file, show the same certificate icon but display "ไม่มีไฟล์แนบ".

Important constraints:

- Do NOT change database schema.
- Do NOT break certificate download/open behavior.
- Keep Thai UI.
- Keep responsive behavior.
- Minimal-impact changes only.

Display rules:

Case 1: Image file exists and preview loads

- Show image preview.

Supported preview image types:

- jpg
- jpeg
- png
- webp
- gif

Case 2: File exists but is not previewable
Examples:

- pdf
- docx
- xlsx
- pptx
- zip
- image preview fails

Show placeholder:

- Certificate icon
- Text: เกียรติบัตร
- File type, e.g. PDF, DOCX, XLSX

Case 3: No file attached
Show placeholder:

- Certificate icon
- Text: ไม่มีไฟล์แนบ

Do NOT show:

- broken image icon
- "-"
- empty cell

Recommended icon:

- Award
  or
- FileBadge
  or
- FileCheck

UI requirement:

- Same card size for image, PDF, and no attachment states.
- Center icon and text.
- Border should be dashed or light border.
- Text should be small and readable.
- Works inside table cell.

Files likely involved:

- src/features/training-records/components/training-record-certificate-manager.tsx
- src/features/training-records/components/training-record-view-page.tsx
- src/features/training-records/components/training-record-tables/columns.tsx
- src/components/certificate-preview.tsx if exists

Output Review File:
Create:
docs/management-change-certificate-empty-state-review.md

Manual Test Checklist:

- Image certificate displays preview.
- PDF certificate shows certificate icon and PDF.
- DOCX certificate shows certificate icon and DOCX.
- Broken image shows certificate icon.
- No attachment shows certificate icon and "ไม่มีไฟล์แนบ".
- No table cell displays "-".
- Download/open still works when file exists.
- Mobile/table layout does not break.
