fix: resize handle now adjusts column to its left

Handle on the left edge resizes the PREVIOUS column, not itself.
This matches the mental model: dragging the boundary between Subject
and Status changes Subject's width. First column has no handle.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

web/src/app/page.tsx

@@ -890,16 +890,19 @@ function TicketWorkbenchContent() {
                     density === "compact" ? "min-h-7" : "min-h-8"
                   )} style={{ display: "table-row" }}>
                     <div style={{ display: "table-cell", width: 36 }} />
-                    {availableColumns.filter((c) => c.visible).map((col) => (
+                    {availableColumns.filter((c) => c.visible).map((col, idx, arr) => (
                       <div
                         key={col.key}
                         className="relative border-r border-border/60 px-3 align-middle last:border-r-0"
                         style={{ display: "table-cell", width: col.key === "subject" ? undefined : col.width }}
                       >
-                        <div
-                          className="absolute left-0 top-0 h-full w-2 -ml-1 cursor-col-resize hover:bg-primary/40 z-10"
-                          onMouseDown={(e) => handleColumnResize(col.key, e)}
-                        />
+                        {/* Resize handle: drags the boundary, resizes the column to the LEFT */}
+                        {idx > 0 && (
+                          <div
+                            className="absolute left-0 top-0 h-full w-2 -ml-1 cursor-col-resize hover:bg-primary/40 z-10"
+                            onMouseDown={(e) => handleColumnResize(arr[idx - 1].key, e)}
+                          />
+                        )}
                         <span className="text-[10px] font-semibold uppercase text-muted-foreground/60 truncate block">
                           {col.label}
                         </span>