chore(lint): drop unused imports flagged at HEAD

eslint was red at HEAD (5b715ac) in files untouched by this branch: unused statSync/dirname (check-plugin-api.mjs), unused PrefsSchema (src/index.ts, tests/smoke.spec.ts) and two Function types (tests/smoke.spec.ts). No behaviour change.

tests/smoke.spec.ts

@@ -11,7 +11,6 @@ import { join, resolve as resolvePath } from 'node:path'
 import { SettingsConflictError, type SettingsNamespace } from '@deepseek-ai/dsh-settings'
 import { apply, mediaTypeForPath, wsCloseReasonOf } from '../src/index.ts'
 import { SidebarError } from '../src/wire.ts'
-import { PrefsSchema } from '../src/config.ts'
 import { SIDEBAR_PREFS_DEFAULTS } from '../src/prefs-shared.ts'
 import { encodeHtmlUrl } from '../src/html-route.ts'
 import * as git from '../src/git.ts'
@@ -892,7 +891,10 @@ describe('side card settings routes', () => {
       effect: (fn: () => void | (() => void)) => { fn() },
       inject: (deps: string[], callback: (sctx: { settings: unknown }) => void) => {
         if (deps.includes('settings') && settings !== undefined) {
-          const s = settings as { update: Function; describe: Function }
+          const s = settings as {
+            update: (ns: string, ...rest: unknown[]) => unknown
+            describe: (ns: string, ...rest: unknown[]) => unknown
+          }
           // Wrap update to emit `settings/document-updated` after each write,
           // mirroring the real SettingsForms service behavior.
           const origUpdate = s.update.bind(s)