bug: unhandled error (InternalServerException) when analysing images larger than 2.5MB

### Checks

- [x] I have searched [github.com/aws/amazon-q-developer-cli/issues](https://github.com/aws/amazon-q-developer-cli/issues?q=) and there are no duplicates of my issue

### Operating system

mac os Sequoia 15.5

### Expected behaviour

I would expect in q chat reported an error about exceeding image file size.

### Actual behaviour

This is the error reported in the q chat:
Amazon Q is having trouble responding right now:
0: unhandled error (InternalServerException)
1: service error
2: unhandled error (InternalServerException)
3: Error { code: "InternalServerException", message: "Encountered an unexpected error when processing the request, please try again.", aws_request_id: "892e6fe5-a769-4fda-8d42-4124d12e8715" }

Location:
crates/chat-cli/src/cli/chat/mod.rs:1215

Backtrace omitted. Run with RUST_BACKTRACE=1 environment variable to display it.
Run with RUST_BACKTRACE=full to include source snippets.

### Steps to reproduce

ask q chat to analyze an image larger than 2.5MB.

Start in crates/chat-cli/src/cli/chat/mod.rs at line 1215 and reproduce the problem by asking Q chat to analyse an image larger than 2.5MB. Trace how the InternalServerException is surfaced and make the completed behavior report that the image exceeds the allowed file size.

Scritto dal modello di indicizzazione a partire dal testo della issue.