Improve CLI account asset display for non-fungible assets

### Feature description

Non-fungible assets should be displayed with a richer, human-friendly format in `miden-cli account` output.

Proposed behavior:
- Detect non-fungible assets when listing account assets.
- Show a stable unique identifier (nonce/serial) and a compact metadata summary if available.
- Keep fungible asset output unchanged; if more detail is needed, consider a `--verbose` or `--json` path.

This is about output clarity in the CLI, not the `mint` command rename (#1599).

### Why is this feature needed?

Current CLI output makes non-fungible assets look like fungibles, which hides ownership/identity details and makes it hard to verify assets or debug account state from the terminal.

Look for the CLI command that lists account assets, likely in a `cli` or `commands` module. Find where asset data is formatted for display. Identify how to distinguish non-fungible assets (likely by type or metadata) and modify the display logic to show a stable identifier and metadata summary. Run the CLI to test the new output format.

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