render pasted images inline with lightbox expansion (T-236, T-254, D-89)

A pasted-image @<path> token now renders as an inline, keyboard-activatable
thumbnail in the Claude conversation that opens the full image in the lightbox;
the composer's attachment chips use the same (larger, 44px) thumbnail. New
ImageThumbnail + openImageLightbox in the Claude layer; ClideMarkdown gains an
onImageToken builder seam (mirroring onRecordTap) that drops a WidgetSpan into
the text flow — it owns no Image.file/lightbox, staying generic. Missing files
degrade to a placeholder; render-only (the sent text + copyText are unchanged).

Resolves the conflicting T-236 (inline thumbnail) / T-254 (image card) designs
into the hybrid the user chose; recorded as D-89.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -18,6 +18,12 @@ heading, and (b) bumping `pubspec.yaml` `version:` in the same commit.
 
 ### Added
 
+- **Pasted images render inline in the Claude conversation.** A pasted-image
+  `@<path>` reference now shows as a bounded thumbnail in the message instead of
+  the raw path; clicking it (or pressing Enter when focused) opens the full
+  image in the lightbox. The composer's attachment previews use the same,
+  larger thumbnail. A missing file degrades to a placeholder; the text sent to
+  Claude is unchanged. (T-236, T-254, D-89)
 - **The editor honours `.editorconfig`.** Opening a file resolves the
   workspace rules into a source-agnostic `EditorSettings` (own INI parser +
   glob matcher, `root`/nearest-wins precedence — no new dependency). The editor