feat(blog): custom hero, OG and blog card images for articles

[simonhamp]

What

Articles can now have a custom hero image uploaded in the admin. From that single upload, three derivatives are generated, each with its own admin-adjustable crop:

• Social (OG) image — 1200×630 (TheOG's dimensions), written to the same og-images/{slug}.png path, so it replaces the TheOG-generated image in og:image/Twitter meta while a hero exists. Remove the hero and the article reverts to TheOG generation.
• Blog card preview — 1200×450, rendered flush at the top of /blog cards (≤200px tall, clipped by the card's rounded corners).
• Article header — 2048×1000 (2× retina), rendered at the top of the article page at up to 500px tall.

Also renames the admin Articles section to Blog (nav label, breadcrumb, list title — no class renames) and stacks the article form labels instead of inline.

How

• ImageCropper Filament field (app/Filament/Forms/Components/ImageCropper.php + blade): a dependency-free Alpine crop tool — aspect-locked drag/resize selection box storing {x, y, width, height} rects as JSON. Crops are non-destructive and re-adjustable at any time without re-uploading. The Croppie plugin was considered but it requires Filament ^3.2 (this app is on v5) and only supports destructive upload-time crops, one file per field.
• ArticleImageService: scales oversized heroes down in place (max 2400px wide), generates the three crops via Intervention Image (already a direct dependency), clamps/centers invalid or missing crop rects, and handles file cleanup when the hero is replaced, the slug changes, the hero is removed, or the article is deleted.
• Uploads validated to min 1200×630. Crop selections appear after saving (create redirects to edit); replacing the hero resets crops to centered defaults.

Testing

• 13 feature tests covering derivative generation/dimensions, crop selection + clamping, hero downscaling, TheOG fallback, file lifecycle, page rendering, and the Filament save flows.
• Full suite green: 1199 tests. Note: the full suite needs memory_limit > 128M (peaks ~259MB) — this is pre-existing (confirmed on a clean main worktree), Herd's default CLI limit fails partway through the suite either way.
• Verified end to end in the browser: cropper init/restore math, UI save → regenerated OG image reflecting the selected crop (pixel-checked), card/header/og:image rendering, and deletion cleanup.

🤖 Generated with Claude Code