feat(start): recent files as a list, icons or large previews

Three toggles beside the Recent Documents title switch the panel between
the existing list, a grid of thumbnail tiles and one large preview per
file. The choice is kept in the recent section of the app config.

Refs #1494

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/app/config.rs

@@ -518,6 +518,8 @@ pub struct RecentConfig {
     pub files: Vec<String>,
     /// How many recent files to keep.
     pub limit: usize,
+    /// List, icons or large previews.
+    pub view: super::RecentView,
 }
 
 impl Default for RecentConfig {
@@ -525,6 +527,7 @@ impl Default for RecentConfig {
         Self {
             files: Vec::new(),
             limit: super::recent::RECENT_DEFAULT,
+            view: super::RecentView::default(),
         }
     }
 }