Move to @pezkuwi/dev 0.86.4 (eslint 10 toolchain)

- dev ^0.86.4 at the root and in packages/apps; directives renamed by
  pezkuwi-dev-migrate-eslint10.
- eslint --fix with the 0.86.4 config; one fix broke syntax
  (typescript-eslint prefer-optional-chain turned
  `(isStarted && onStart) && onStart()` into `(isStarted && onStart?.();`
  in TxButton) and is corrected by hand.
- The remaining findings fixed rather than disabled: optional chains
  (each suggestion reviewed), `cause` on rethrown errors, `if` instead of
  `a && promise` in effects, parallel instead of sequential awaits in
  Promise.all, Error rejections, no `delete` on arrays (the storage query
  cache is a Map; an upload's file list no longer keeps a hole), no
  `[object Object]` stringification (TFunction's second argument is text
  or options), dead code removed (referenda's never-shown expand button,
  react-query's unused CoreDescriptor).

packages/apps-config/src/api/spec/interbtc.ts

@@ -1,8 +1,6 @@
 // Copyright 2017-2026 @pezkuwi/apps-config authors & contributors
 // SPDX-License-Identifier: Apache-2.0
 
-/* eslint-disable @typescript-eslint/no-unsafe-argument, @typescript-eslint/no-unsafe-member-access, @typescript-eslint/no-unsafe-assignment */
-
 import type { Observable } from 'rxjs';
 import type { ApiInterfaceRx } from '@pezkuwi/api/types';
 import type { DeriveBalancesAll } from '@pezkuwi/api-derive/types';
@@ -21,7 +19,6 @@ function balanceOf (number: number | string): U128 {
 }
 
 function defaultAccountBalance (): DeriveBalancesAll {
-  // eslint-disable-next-line @typescript-eslint/no-unsafe-return
   return {
     accountNonce: new BN(1),
     additional: [],