fix: simplify revision diff selection into a flat list

Revisions still used ancestry lanes and placed author/date/bookmark metadata before the summary. Show short change IDs and summaries first, move metadata to a dimmed detail row, and remove the obsolete picker graph projection.

tests/unit/tui.rs

@@ -3561,7 +3561,7 @@ fn checkout_picker_labels_follow_the_configured_stage() {
 }
 
 #[test]
-fn jj_picker_renders_graph_before_badge_and_compacts_without_losing_controls() {
+fn jj_revision_picker_keeps_summaries_and_before_visible_without_graph_lanes() {
     use crate::diff::{Category, RepoKind, Revision, RevisionGraph, RevisionTarget};
     let mut catalog = diff_catalog();
     catalog.kind = RepoKind::Jujutsu;
@@ -3582,10 +3582,10 @@ fn jj_picker_renders_graph_before_badge_and_compacts_without_losing_controls() {
                 change_id: change.into(),
                 description: format!("{change} description"),
                 parents: parent.into_iter().map(str::to_owned).collect(),
-                author: "alice".into(),
+                author: "An author whose name must not displace the summary".into(),
                 timestamp: "2026-10-23".into(),
                 bookmarks: if current {
-                    "main".into()
+                    "vl/fin-1441-1-ora-edi-recovery@origin".into()
                 } else {
                     String::new()
                 },
@@ -3606,10 +3606,16 @@ fn jj_picker_renders_graph_before_badge_and_compacts_without_losing_controls() {
     render_diff(&mut terminal, &diff, &mut panels);
     let text = screen_text(&terminal);
     assert!(text.contains("Choose After"));
-    assert!(text.contains("@"));
-    assert!(text.contains("change-a [Before] alice 2026-10-23 [main] aaaa1111"));
-    assert!(text.contains("change-a description"));
-    assert!(!text.contains("Before:"));
+    let summary = text
+        .lines()
+        .find(|line| line.contains("change-a description"))
+        .unwrap();
+    assert!(summary.contains("[Before]"), "{text}");
+    assert!(!summary.contains("An author"), "{text}");
+    assert!(
+        !text.contains('~') && !text.contains('○') && !text.contains('◆'),
+        "{text}"
+    );
     let buffer = terminal.backend().buffer();
     let selected_rows: Vec<_> = (0..buffer.area.height)
         .filter(|&y| (0..buffer.area.width).any(|x| buffer[(x, y)].bg == Color::Blue))