[Zed] Agent Panel: Pasting image file inserts image instead of filename

### Reproduction steps 1. In Finder, select an image file (PNG, JPEG, etc.) 2. Copy it with `Cmd+C` (or right-click → Copy) 3. Open the Agent Panel in Zed 4. Paste with `Cmd+V https://github.com/user-attachments/assets/ac7cfc4b-c358-4f52-bb5b-861f10849f76 ### Current vs. Expected behavior Current: The file path is inserted as plain text, e.g.: ``` /Users/username/Desktop/Screenshot 2026-03-15 at 5.08.22 AM.png ``` Expected: The image is attached as a context mention (same as drag-and-drop or `Cmd+Shift+4` screenshot paste). ### Zed version and system specs Zed: v0.227.1+stable.199.9f9b707d39d62468d4cdaed2d8eb95a847da4cf9 (Zed) OS: macOS 26.2 Memory: 32 GiB Architecture: aarch64 ### Attach Zed log file <details><summary>Zed.log</summary> <!-- Paste your log inside the code block. --> ```log ``` </details> ### Relevant Zed settings <details><summary>settings.json</summary> <!-- Paste your settings inside the code block. --> ```json ``` </details> ### Relevant Keymap