Configurable list columns via header right-click

Native checkable menu on the column headers toggles Size, Modified,
Kind, Rights, Owner and Group (persisted, both panels). Owner/group
come from the ls-style SFTP longname remotely and cached uid/gid
lookups locally (POSIX; undefined on Windows). All columns sort.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/shared/types.ts

@@ -7,8 +7,13 @@ export interface FileEntry {
 	size: number; // bytes
 	mtime: number; // epoch milliseconds
 	mode: number; // permission bits only (masked & 0o7777)
+	owner?: string; // resolved name when the provider knows it
+	group?: string;
 }
 
+/** Optional file-list columns (Name is always shown). */
+export type ColumnKey = "size" | "mtime" | "kind" | "rights" | "owner" | "group";
+
 /** Every RPC response uses this envelope; errors never cross the bridge as exceptions. */
 export type Result<T = object> = ({ ok: true } & T) | { ok: false; error: string };
 
@@ -75,6 +80,8 @@ export interface AppSettings {
 	accent: AccentTone;
 	/** File-list icons: plain neutral glyphs, or per-category glyphs and colors. */
 	iconColors: "plain" | "multi";
+	/** Visible optional file-list columns (both panels; Name always shows). */
+	columns: ColumnKey[];
 	speedUnit: "MBps" | "Mbps";
 	/** Size of the panel interface: file list, path bar, header controls. */
 	textSize: "compact" | "default" | "large";
@@ -95,6 +102,7 @@ export const DEFAULT_SETTINGS: AppSettings = {
 	darkTone: "dark",
 	accent: "blue",
 	iconColors: "multi",
+	columns: ["size", "mtime"],
 	speedUnit: "MBps",
 	textSize: "default",
 	transferMode: "single",