fix: keep the resource AppConnect fills when linking its account fails

Deleting a variable also deletes the resource at its path, so the rollback
is skipped when filling an existing resource.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/lib/components/AppConnectInner.svelte

@@ -1011,11 +1011,14 @@
 								requestBody: { ...accountData, variable_path: tokenPath }
 							})
 						} catch (e) {
-							// An unlinked token never refreshes, and its path would block a retry.
-							await VariableService.deleteVariable({
-								workspace: effectiveWorkspace,
-								path: tokenPath
-							}).catch(() => {})
+							// An unlinked token never refreshes, and its path would block a retry. Not when
+							// filling: deleting a variable also deletes the resource at its path.
+							if (!filling) {
+								await VariableService.deleteVariable({
+									workspace: effectiveWorkspace,
+									path: tokenPath
+								}).catch(() => {})
+							}
 							throw e
 						}
 					}