Add column visibility toggle and drag-sort via settings modal

- Remove default workshop number from search input
- Add ColumnSettingsModal with checkboxes for show/hide per column
- Add drag-and-drop reordering using @dnd-kit/sortable
- Persist column config to localStorage across sessions
- Include search filter, select all/deselect all/reset defaults

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

package-lock.json

@@ -9,6 +9,9 @@
       "version": "0.1.0",
       "dependencies": {
         "@ant-design/icons": "^6.2.5",
+        "@dnd-kit/core": "^6.3.1",
+        "@dnd-kit/sortable": "^10.0.0",
+        "@dnd-kit/utilities": "^3.2.2",
         "antd": "^6.4.3",
         "mssql": "^12.5.5",
         "next": "16.2.9",
@@ -625,6 +628,60 @@
         "node": ">=6.9.0"
       }
     },
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+      "license": "MIT",
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+      "peerDependencies": {
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+      "license": "MIT",
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+      "dependencies": {
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+        "@dnd-kit/utilities": "^3.2.2",
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+        "react": ">=16.8.0"
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     "node_modules/@emnapi/wasi-threads": {
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       "resolved": "https://registry.npmmirror.com/@emnapi/wasi-threads/-/wasi-threads-1.2.2.tgz",