[Fix] Fix NaN position in notes resulting in not being able to create notes (#16818)

Following [discord
thread](https://discord.com/channels/1130383047699738754/1453910755387899996/1453910755387899996),
reproductible on twenty-eng


https://github.com/user-attachments/assets/ae7f363d-87e1-44fa-8fe2-ee78412d62a7

Records positions are computed at record creation, depending on the
position arg from the request, being equal to `last`, `first`, or not
present.
When being equal to last, as it is done when creating a note from the
product, the position is calculated using `.maximum()` function which
uses postgres' MAX function. If there is a `NaN` value among the list,
the MAX will return `NaN` too. So if for some reason there is a NaN
somewhere in the position column, all subsequent records being created
with last position argument will be created with NaN value. Until [this
PR](https://github.com/twentyhq/twenty/pull/16630), where we introduced
a validation on position at record creation which throws when NaN is
trying to be introduced as a position, this was going silent. (fyi
@etiennejouan , not on you at all but for info)

Looking into twenty-eng workspace, I found note records with NaN
position dating back to august 2025, making it hard to understand and
debug why they were introduced with NaN position. So I did not find the
real root cause, but I suggest to
- update record-position.service to fix the issue for subsequent records
that go through this service (which is what is currently broken)
- run a command to fix the existing records with NaN position for Notes,
as it is where the issue happened for both the user reporting the issue
on discord, and us on twenty-eng. So hopefully the problem was limited
to Notes

packages/twenty-server/src/engine/utils/sanitize-number.utli.ts

@@ -0,0 +1,8 @@
+import { isDefined } from 'twenty-shared/utils';
+export const sanitizeNumber = (value: number | null): number | null => {
+  if (!isDefined(value) || Number.isNaN(value)) {
+    return null;
+  }
+
+  return value;
+};