Decompose BoardPage into individual components and remove debug logging.

Extract BoardRow, BoardColumn, BoardViewHeader, BoardEditHeader, and
boardConstants into separate files. Remove 9 console.log statements
from BoardBody and BoardProvider.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/app/(main)/boards/[boardId]/BoardColumn.tsx

@@ -0,0 +1,52 @@
+import { Box, Button, Column, Icon, Tooltip, TooltipTrigger } from '@umami/react-zen';
+import type { ReactElement } from 'react';
+import { Plus, X } from '@/components/icons';
+
+export function BoardColumn({
+  id,
+  component,
+  editing = false,
+  onRemove,
+  canRemove = true,
+}: {
+  id: string;
+  component?: ReactElement;
+  editing?: boolean;
+  onRemove?: (id: string) => void;
+  canRemove?: boolean;
+}) {
+  const handleAddComponent = () => {};
+
+  return (
+    <Column
+      marginTop="3"
+      marginLeft="3"
+      width="100%"
+      height="100%"
+      alignItems="center"
+      justifyContent="center"
+      backgroundColor="surface-sunken"
+      position="relative"
+    >
+      {editing && canRemove && (
+        <Box position="absolute" top="10px" right="20px" zIndex={100}>
+          <TooltipTrigger delay={0}>
+            <Button variant="quiet" onPress={() => onRemove?.(id)}>
+              <Icon size="sm">
+                <X />
+              </Icon>
+            </Button>
+            <Tooltip>Remove column</Tooltip>
+          </TooltipTrigger>
+        </Box>
+      )}
+      {editing && (
+        <Button variant="outline" onPress={handleAddComponent}>
+          <Icon>
+            <Plus />
+          </Icon>
+        </Button>
+      )}
+    </Column>
+  );
+}