Fix history pane ordering, scrolling, and live updates

- Fix history ordering to show newest edits first (index 0 = newest)
- Fix scrollToChange() to calculate correct viewport offset for context-limited rendering
- Support flat JSON format in parsePayload() for daemon/hook notifications
- Fix navigation keys (j=down to older, k=up to newer)
- Limit file rendering to 100 lines of context for performance
- Use fixed 1/3 width for left pane to prevent layout shifts
- Pad history list to consistent height to prevent UI warping
- Remove variable-height commit headers from history list

Author: zach-source

internal/daemon/daemon.go

@@ -300,6 +300,8 @@ func (d *Daemon) processPayload(payload *HookPayload) error {
 					logger.Log("Compressed file snapshot: %d bytes -> %d bytes", len(decoded), len(edit.FileSnapshot))
 				}
 			}
+		} else {
+			logger.Log("No file_content_b64 provided for %s (file: %s)", payload.ToolName, payload.FilePath)
 		}
 
 		if err := d.db.RecordEdit(edit); err != nil {