List view metadata columns and drag-to-resize everywhere

- New optional list-view columns: Description, Size (now includes
  directories), Modified, Owner, Created (via statx birth time), Content
  (item/line count or image dimensions), Access (rwx)
- Drag-to-resize: list view column headers, sidebar sections (Bookmarks/
  Devices/Filetree), Preview/Tags split, and the sidebar/preview side
  panels themselves — all commit to Config on release, not per drag frame
- Column resizing mutates existing row cells live instead of rebuilding,
  with metadata cached per (file, mtime) — fixes lag in large folders
- Fix list view background click (rows were full ListTile width with no
  empty space to click); bookmark selected-background now covers the
  triple-dot menu too; batch rename/new-file dialogs pre-select their
  default text instead of just pre-filling it
- Toolbar scrolls instead of clipping when buttons don't fit; toolbar and
  breadcrumbs are independently toggleable
- Add a "Server" bookmark icon

Co-Authored-By: Claude Sonnet 5 <[email protected]>

Core.py

@@ -9,6 +9,7 @@ import shutil
 import subprocess
 from dataclasses import asdict, dataclass, field
 from pathlib import Path
+from typing import Callable, Optional
 
 import flet as ft
 import toml
@@ -170,6 +171,27 @@ class AppConfig:
 
     ShowDotfiles: bool = True
     ViewMode: str = "list"  # "list" or "grid"
+    # List view: which metadata columns show, beyond the always-present Name.
+    ListShowDescription: bool = False
+    ListShowSize: bool = True
+    ListShowModified: bool = True
+    ListShowOwner: bool = False
+    ListShowCreated: bool = False
+    ListShowContent: bool = False
+    ListShowAccess: bool = False
+    # List view column widths — drag the header dividers to set these, or
+    # type a number in Options; both write here.
+    ListWidthName: int = 220
+    ListWidthDescription: int = 90
+    ListWidthSize: int = 80
+    ListWidthModified: int = 130
+    ListWidthOwner: int = 90
+    ListWidthCreated: int = 130
+    ListWidthContent: int = 90
+    ListWidthAccess: int = 60
+    # Grid view.
+    GridIconSize: int = 64
+    GridNameBelowIcon: bool = True
 
     # Batch-rename pattern for multi-select rename, syntax modeled on
     # SaraSortd's own placeholder characters (see ~/Applications/SaraSortd's
@@ -403,6 +425,46 @@ def ApplyHeightBounds(Content: ft.Control, MinHeight: int, MaxHeight: int) -> ft
     return Content
 
 
+def ResizeHandle(
+    Axis: str,
+    Length: Optional[int],
+    OnDrag: Callable[[float], None],
+    OnDragEnd: Callable[[], None],
+) -> ft.GestureDetector:
+    """A thin draggable divider, shared by the file list's column headers,
+    the sidebar/preview section splits, and the sidebar/preview *panel*
+    widths. "horizontal" resizes side-by-side things (drag left/right, e.g.
+    a column or a whole side panel) and needs Length = the row's height, not
+    just 6px wide with an unset (collapses to zero) height; "vertical"
+    resizes stacked things (drag up/down, e.g. Bookmarks vs Devices) and
+    needs Length = the panel's width, for the same reason on the other axis.
+    Pass Length=None instead when the immediate parent Row/Column already
+    stretches its children on that cross axis (confirmed, not assumed —
+    Flet doesn't do this by default) — then an explicit value would fight
+    that stretch instead of matching it. OnDrag fires with the incremental
+    delta on every move — cheap for a single header cell or a sidebar
+    section, but callers with many redraws to do (the file list's rows)
+    should treat it as a live *preview* and do the expensive rebuild in
+    OnDragEnd instead, which fires once on release; that's also where
+    Config gets saved, so a drag isn't disk I/O on every pixel of movement."""
+    IsHorizontal = Axis == "horizontal"
+    Handle = ft.GestureDetector(
+        content=ft.Container(
+            width=6 if IsHorizontal else Length,
+            height=Length if IsHorizontal else 6,
+            bgcolor=Palette.Surface1,
+        ),
+        mouse_cursor=ft.MouseCursor.RESIZE_COLUMN if IsHorizontal else ft.MouseCursor.RESIZE_ROW,
+    )
+    if IsHorizontal:
+        Handle.on_horizontal_drag_update = lambda e: OnDrag(e.primary_delta or 0)
+        Handle.on_horizontal_drag_end = lambda e: OnDragEnd()
+    else:
+        Handle.on_vertical_drag_update = lambda e: OnDrag(e.primary_delta or 0)
+        Handle.on_vertical_drag_end = lambda e: OnDragEnd()
+    return Handle
+
+
 # The group tag shared by every Draggable source and DragTarget in the app,
 # so bookmarks/filetree only accept drops that actually originate from
 # SaraFem's own file list (not, say, a Chip or some future draggable widget).