[Feature]: Integrate GStreamer errors with `ImageError` for unified upstream handling

Support bridging GStreamer-related errors into ImageError so upstream code can handle image and stream failures more consistently.

Motivation

When image-processing and video I/O paths use different error hierarchies, application code often needs extra conversion or matching logic. A clearer bridge to ImageError would make higher-level integration simpler and more consistent.

Proposed Solution

• Review current GStreamer error variants and identify where ImageError mapping makes sense.
• Add conversions or wrapper types where appropriate.
• Preserve useful GStreamer-specific context instead of collapsing errors too aggressively.
• Update tests and docs for the new error behavior.

Expected Outcome

Upstream code gets a more consistent and ergonomic error-handling story across image and video APIs.

✅ Acceptance Criteria

• The TODO for ImageError integration is resolved.
• Error conversions are documented.
• At least one representative test covers the bridging behavior.
• Existing error information is preserved as much as possible.

Additional Context

This is primarily an API and ergonomics issue rather than a raw performance issue. It may require maintainer guidance to avoid awkward dependency or layering decisions.

Code Reference

// crates/kornia-io/src/gstreamer/error.rs ~40
// TODO: support later on ImageError

🤝 Contribution Intent

• I plan to submit a PR to implement this feature
• I'm requesting this feature but not planning to implement it