Render image previews for read tool image results

[ashwin-pc]

Problem

When the read tool reads an image file, the tool card only shows the placeholder text instead of the image:

Read image file [image/png]
[Image: original 1905x2053, displayed at 1856x2000. Multiply coordinates by 1.03 to map to original image.]
[image]

We should show an actual preview of the image when the card is expanded.

Implementation

• Server: new GET /api/file/image?path=<path> endpoint (server.ts) that serves an image file from the workspace by path. Validates the path is within piCwd and has an image extension.
• Frontend (src/tools/toolCards.ts): for successful read results that are images, render an <img> preview instead of the text note.
  • Prefers inline base64 image data when present (live executions / non-stripped results).
  • Falls back to fetching the file by path via the new endpoint (persisted history strips the base64 data, so this is the primary path for reloaded sessions).
  • Reuses attachImageActions for fullscreen / download / open-in-new-tab.
• Raw result content is now threaded through the history render path (AddToolHistoryCard gains an optional rawResult) so inline images survive a refresh.
• Added .toolCardImage styles.

Tests

• Added a read image mock case (server/mock.ts) returning an inline base64 image.
• Added an e2e test asserting an <img> preview renders and no text body is shown.