feat: improve attachment preview cards

[Abysstsuki]

Summary

• Add display-name-aware attachment references so newly sent desktop messages can preserve original filenames in history.
• Update composer attachment cards with image-first ordering, larger image thumbnails, aligned remove controls, and rectangular file cards.
• Update user-message attachment cards to match the composer preview layout, including image thumbnail loading for stored image attachments.

Scope

This is a frontend display change only. The submitted model input still uses the existing @.reasonix/attachments/... references, and the backend attachment storage / reference resolution flow is unchanged.

Testing

• npx.cmd tsx src/__tests__/attachment-display.test.ts
• npm.cmd run test:typecheck
• npm.cmd run check:css

[esengine]

Reviewed. The display/submit split is handled correctly — the named @[label](path) form only ever exists in the display string, the model still receives the raw @.reasonix/attachments/… refs, and the parser keeps backward compatibility with unnamed refs. baseName growing backslash awareness and the escaped-bracket cleanup in labels are the right edge cases to have covered, and sortDisplayAttachments relying on stable sort keeps non-image relative order intact.

One small thing I'll fix in a follow-up rather than another round here: attachment-display.test.ts isn't wired into the test/test:all scripts in package.json (the suite enumerates files explicitly), so CI never runs it as-is.

Merging — the composer/message card alignment is a clear visual upgrade. Thanks!