Add focus-aware crop suggestions

[jeffpaul]

What problem does this address?

Users (who know they can and actually change their image crops) spend time manually finding the best crop and focal point, especially for featured images and responsive layouts. The focal point selector feature (WordPress/gutenberg#75221) creates a natural UI surface to add AI-assisted suggestions.

What is your proposed solution?

Add “Suggest focal point” and “Suggest crops” actions in the Gutenberg-based Media Editor UI tied to the focal point selector (WordPress/gutenberg#75221) as well as within the Media Library's Edit Media screen.

Suggestions should:

• Detect primary subject(s)
• Recommend a focal point plus 2–3 crop presets (square, portrait, landscape)

Save the selected focal point metadata and (optionally) store suggested crops as metadata for reuse.

[TylerB24890]

I've got an experiment for this created here: #494 -- there is no UI developed for it yet since the Focal Point Picker isn't yet integrated into the Media Editor, but it can be tested through the Abilities Explorer (instructions in the PR description).