fix(tui): pasted U+2028 and U+2029 become line breaks

str::lines() splits on neither separator, so a paste carrying them counted
as one line and the invisible characters broke the textarea's width model.
Bare \r, U+2028 and U+2029 now normalize to \n on every paste route (the
prompt, the inline paste key and the previous-message editor); dropped
file paths keep their bytes verbatim because a separator in a filename is
payload.

Ported from upstream 1.0.18 (grok-build prompt_widget normalize_line_breaks).

Claude-Session: https://claude.ai/code/session_01RUqV8HVGXcAETyYbZ2tPQ4

crates/codegen/kigi-tui/src/app/agent_view/input.rs

@@ -734,7 +734,8 @@ impl AgentView {
                 Event::Mouse(mouse) => self.handle_inline_edit_mouse(mouse),
                 Event::Paste(text) => {
                     if let Some(ref mut edit) = self.inline_edit {
-                        edit.textarea.insert_str(text);
+                        edit.textarea
+                            .insert_str(&crate::views::prompt_widget::normalize_line_breaks(text));
                     }
                     InputOutcome::Changed
                 }

crates/codegen/kigi-tui/src/app/agent_view/paste.rs

@@ -344,7 +344,10 @@ impl AgentView {
                         self.prompt.textarea.begin_undo_group();
                         group_open = true;
                     }
-                    if matches!(self.prompt.handle_paste(&to_insert), PromptEvent::Edited) {
+                    if matches!(
+                        self.prompt.insert_dropped_path(&to_insert),
+                        PromptEvent::Edited
+                    ) {
                         inserted_non_image = true;
                     }
                 }

crates/codegen/kigi-tui/src/app/inline_edit.rs

@@ -290,6 +290,27 @@ mod tests {
         agent
     }
 
+    /// The previous-message editor is its own paste route; separators normalize there too.
+    #[test]
+    fn inline_edit_paste_normalizes_line_separators() {
+        let mut agent = agent_with_prompt();
+        assert!(agent.enter_inline_edit(0));
+        let registry = crate::actions::ActionRegistry::defaults();
+        agent.handle_input(
+            &crossterm::event::Event::Paste("a\u{2028}b\u{2029}c".into()),
+            &registry,
+        );
+        let text = agent
+            .inline_edit
+            .as_ref()
+            .expect("editing state")
+            .textarea
+            .text()
+            .to_owned();
+        assert!(text.contains("a\nb\nc"), "{text:?}");
+        assert!(!text.contains('\u{2028}'), "{text:?}");
+    }
+
     /// Entering edit mode on a plain user prompt captures the original text,
     /// resolves the rewind target, and selects the entry.
     #[test]