BUG: Job Center cards are not keyboard accessible

**Describe the bug**
On the Job Center page, each job card is clickable only with a mouse because the card root is a `div` with an `onClick` handler instead of a semantic link/button. The card does not receive keyboard focus, so keyboard users cannot open a job detail page. The job logo image in each card also has no `alt` text.

**To Reproduce**
Steps to reproduce the behavior:
1. Go to 'https://kubeedge.io/job-center/'
2. Press `Tab` after the header section to move through interactive elements
3. Observe that the job cards do not receive focus and cannot be opened with the keyboard
4. Inspect a job card logo image and observe that it does not provide any `alt` text

**Expected behavior**
Each job card should be reachable and activatable from the keyboard using semantic navigation markup, and the logo image should expose meaningful alternative text.

**Screenshots**
N/A. This accessibility issue is not visually obvious in the UI. It was reproduced through keyboard navigation and DOM inspection.

**Desktop (please complete the following information):**
- OS: Windows
- Browser: Chromium-based browser
- Version: N/A

**Smartphone (please complete the following information):**
- Device: N/A
- OS: N/A
- Browser: N/A
- Version: N/A

**Additional context**
Current implementation in `src/components/jobCard/index.js` uses a clickable `div` for navigation and renders `` without an `alt` attribute.