refactor(cli): adopt flex-width rendering, remove data-layer truncation

Replace hardcoded truncation widths across CLI commands with
render::flex_width() calls that adapt to terminal size. Remove
server-side truncate_to_chars() in timeline collect/seed stages so
full text is preserved through the pipeline — truncation now happens
only at the presentation layer where terminal width is known.

Affected commands: explain, file-history, list (issues/mrs/notes),
me, timeline, who (active/expert/workload).

src/cli/commands/explain.rs

@@ -378,17 +378,10 @@ fn get_mr_assignees(conn: &Connection, mr_id: i64) -> Result<Vec<String>> {
 // Description excerpt helper
 // ---------------------------------------------------------------------------
 
-fn truncate_description(desc: Option<&str>, max_len: usize) -> String {
+fn truncate_description(desc: Option<&str>) -> String {
     match desc {
         None | Some("") => "(no description)".to_string(),
-        Some(s) => {
-            if s.len() <= max_len {
-                s.to_string()
-            } else {
-                let boundary = s.floor_char_boundary(max_len);
-                format!("{}...", &s[..boundary])
-            }
-        }
+        Some(s) => s.to_string(),
     }
 }
 
@@ -413,7 +406,7 @@ pub fn run_explain(conn: &Connection, params: &ExplainParams) -> Result<ExplainR
         };
 
     let description_excerpt = if should_include(&params.sections, "description") {
-        Some(truncate_description(description.as_deref(), 500))
+        Some(truncate_description(description.as_deref()))
     } else {
         None
     };
@@ -537,8 +530,10 @@ const DECISION_WINDOW_MS: i64 = 60 * 60 * 1000;
 
 /// Maximum length (in bytes, snapped to a char boundary) for the
 /// `context_note` field in a `KeyDecision`.
+#[allow(dead_code)]
 const NOTE_TRUNCATE_LEN: usize = 500;
 
+#[allow(dead_code)]
 fn truncate_note(text: &str, max_len: usize) -> String {
     if text.len() <= max_len {
         text.to_string()
@@ -682,7 +677,7 @@ pub fn extract_key_decisions(
                 timestamp: ms_to_iso(event.created_at),
                 actor: event.actor.clone(),
                 action: event.description.clone(),
-                context_note: truncate_note(&note.body, NOTE_TRUNCATE_LEN),
+                context_note: note.body.clone(),
             });
         }
     }
@@ -1257,7 +1252,7 @@ pub fn print_explain(result: &ExplainResult) {
                 Theme::dim().render(&to_relative(&t.last_note_at))
             );
             if let Some(ref excerpt) = t.first_note_excerpt {
-                let preview = render::truncate(excerpt, 100);
+                let preview = render::truncate(excerpt, render::flex_width(8, 30));
                 // Show first line only in human output
                 if let Some(line) = preview.lines().next() {
                     println!("      {}", Theme::muted().render(line));
@@ -1283,7 +1278,7 @@ pub fn print_explain(result: &ExplainResult) {
                 "    {} {} — {} {}",
                 Icons::success(),
                 Theme::mr_ref().render(&format!("!{}", mr.iid)),
-                render::truncate(&mr.title, 60),
+                render::truncate(&mr.title, render::flex_width(25, 20)),
                 mr_state.render(&format!("[{}]", mr.state))
             );
         }
@@ -1305,7 +1300,7 @@ pub fn print_explain(result: &ExplainResult) {
             println!(
                 "    {arrow} {} {}{state_str} ({})",
                 ref_style.render(&format!("{ref_prefix}{}", ri.iid)),
-                render::truncate(ri.title.as_deref().unwrap_or("(untitled)"), 50),
+                render::truncate(ri.title.as_deref().unwrap_or("(untitled)"), render::flex_width(30, 20)),
                 Theme::dim().render(&ri.reference_type)
             );
         }
@@ -1596,14 +1591,13 @@ mod tests {
 
     #[test]
     fn test_truncate_description() {
-        assert_eq!(truncate_description(None, 500), "(no description)");
-        assert_eq!(truncate_description(Some(""), 500), "(no description)");
-        assert_eq!(truncate_description(Some("short"), 500), "short");
+        assert_eq!(truncate_description(None), "(no description)");
+        assert_eq!(truncate_description(Some("")), "(no description)");
+        assert_eq!(truncate_description(Some("short")), "short");
 
         let long = "a".repeat(600);
-        let truncated = truncate_description(Some(&long), 500);
-        assert!(truncated.ends_with("..."));
-        assert!(truncated.len() <= 504); // 500 + "..."
+        let result = truncate_description(Some(&long));
+        assert_eq!(result, long); // no truncation — full description preserved
     }
 
     // -----------------------------------------------------------------------