Rename REFRESH_TOKEN_COOL_DOWN to REFRESH_TOKEN_REUSE_GRACE_PERIOD and anchor the grace window (#17782)

## Summary

- Renames `REFRESH_TOKEN_COOL_DOWN` to
`REFRESH_TOKEN_REUSE_GRACE_PERIOD` — the old name was misleading and
suggested a security mechanism rather than what it actually is: a grace
period for concurrent refresh token use (e.g. two browser tabs
refreshing simultaneously).
- Makes the token revocation in `renew-token.service.ts` conditional
(`revokedAt: IsNull()`), so if the token was already revoked by a
concurrent request, the original `revokedAt` timestamp is preserved and
the grace window stays anchored.
- Updates comments and config description to clarify intent.

## Test plan

- [x] Existing unit tests updated and passing
(`refresh-token.service.spec.ts`, `renew-token.service.spec.ts`)
- [x] Lint clean

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Co-authored-by: Cursor <cursoragent@cursor.com>

packages/twenty-server/src/engine/core-modules/twenty-config/config-variables.ts

@@ -277,12 +277,13 @@ export class ConfigVariables {
 
   @ConfigVariablesMetadata({
     group: ConfigVariablesGroup.TOKENS_DURATION,
-    description: 'Cooldown period for refreshing tokens',
+    description:
+      'Grace period allowing concurrent refresh token use (e.g. two tabs refreshing simultaneously). Reuse after this window triggers suspicious activity detection.',
     type: ConfigVariableType.STRING,
   })
   @IsDuration()
   @IsOptional()
-  REFRESH_TOKEN_COOL_DOWN = '1m';
+  REFRESH_TOKEN_REUSE_GRACE_PERIOD = '1m';
 
   @ConfigVariablesMetadata({
     group: ConfigVariablesGroup.TOKENS_DURATION,