fix #221: scale image pastes, drop text box, fix raw view and size

- image pastes render the image scaled to fit the viewer box (aspect
  ratio preserved, max-height 70vh), no text/code box below it
- link pill moved under the image as a small inline chip
- /raw serves image attachment bytes as an image instead of empty text
- view details size reports the actual attachment file size

internal/web/static/app.css

@@ -216,10 +216,7 @@ body {
 .tag { font-size: 19.8px; color: var(--muted-fg); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 2px 9px; }
 .paste-title-bar { display: flex; align-items: center; gap: 12px; padding: 12px 18px; flex-wrap: wrap; }
 .paste-title-bar h1 { font-size: 29.2px; font-weight: 600; margin: 0; word-break: normal; overflow-wrap: anywhere; }
-/* #222: .float already draws the border + radius and clips corners; the pill's own
+.stats-pill { border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; }
-   tighter border curve was getting clipped thin at the corners. Let .float be the
-   only border/paint surface for the details pill (collapsed and expanded). */
-.stats-pill { border: 0; border-radius: 0; overflow: hidden; }
 .stats-head { display: flex; align-items: center; gap: 16px; width: 100%; background: none; border: 0; border-bottom: 1px solid var(--border); color: var(--muted-fg); font: inherit; font-size: 21.6px; padding: 14px 18px; cursor: pointer; text-align: left; }
 .stats-head:hover { color: var(--fg); background: var(--surface-2); }
 .stats-chev { width: 18px; height: 18px; flex: none; transition: transform 0.15s ease; }