feat: add resizable kanban column width (#21828)

## What & why

Lets users resize the columns of a Kanban (record board) view. Requested
by a user; the design avoids the "ragged board" problem by making the
width a **single shared value**.

## Behaviour

- A drag handle appears on the right edge of every column header.
- Because all columns read **one** width value, dragging any handle
resizes **every** column together — they can never end up mismatched.
- Width is clamped between **150px** and **400px** (default **200px**).
- The width is **persisted per view** and restored on reload.

## Approach

**Backend** — a new nullable `View.kanbanColumnWidth` field, threaded
through the existing view-level setting pattern (the same one
`kanbanAggregateOperation` / `shouldHideEmptyGroups` use), so it gets
create/update/manifest/override support for free:
- entity column + `ViewOverrides` + `@WasIntroducedInUpgrade`
- `CreateViewInput` / `UpdateViewInput` (`Int`, `@Min(150)`/`@Max(400)`)
+ `ViewDTO`
- flat-view editable properties, entity-properties config, compare-type,
standard-view + manifest converters
- a fast instance command adding the `core.view` column

**Frontend** — the value hydrates into a view-scoped atom and drives a
single CSS variable set on the board container, which both column
headers and bodies read. Live dragging only writes that CSS variable (no
per-move React re-render); the final width is committed to the atom and
persisted via `updateView` on pointer-up.

## Nullability / defaults

`kanbanColumnWidth` is nullable — `null` means "never resized" and the
UI falls back to the 200px default, so existing rows need no backfill.

## Validation

- `nx typecheck twenty-server` ✅ and `nx typecheck twenty-front` ✅
- `nx lint:diff-with-main twenty-server` ✅; frontend lint fixes applied
(split constants to one-per-file, removed `useRef`-for-state in favour
of `useState`).
- Draft pending a final green CI run (the dev container reclaimed
`node_modules` mid-session; re-running locally).

## Test plan

- [ ] Drag a kanban column edge → all columns resize together, clamped
150–400px
- [ ] Reload → width persists for that view; other views unaffected
- [ ] A view that was never resized still renders at 200px

https://claude.ai/code/session_016Qe6oDBkhVbrq2QkXBJ5nE

---
_Generated by [Claude
Code](https://claude.ai/code/session_016Qe6oDBkhVbrq2QkXBJ5nE)_

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Co-authored-by: Claude <noreply@anthropic.com>

packages/twenty-server/src/engine/metadata-modules/flat-entity/constant/__tests__/__snapshots__/all-universal-flat-entity-properties-to-compare-and-stringify.constant.spec.ts.snap

@@ -333,6 +333,7 @@ exports[`ALL_UNIVERSAL_FLAT_ENTITY_PROPERTIES_TO_COMPARE_AND_STRINGIFY should ma
       "visibility",
       "mainGroupByFieldMetadataUniversalIdentifier",
       "shouldHideEmptyGroups",
+      "kanbanColumnWidth",
       "isActive",
       "universalOverrides",
     ],

packages/twenty-server/src/engine/metadata-modules/flat-entity/constant/all-entity-properties-configuration-by-metadata-name.constant.ts

@@ -376,6 +376,12 @@ export const ALL_ENTITY_PROPERTIES_CONFIGURATION_BY_METADATA_NAME = {
       universalProperty: undefined,
       isOverridable: true,
     },
+    kanbanColumnWidth: {
+      toCompare: true,
+      toStringify: false,
+      universalProperty: undefined,
+      isOverridable: true,
+    },
     isActive: {
       toCompare: true,
       toStringify: false,