fix: replace as-unknown-as casts with safer patterns (#9107)

## Summary

- Replace 83 `as unknown as` double casts with safer alternatives across
33 files
- Use `as Partial<X> as X` pattern where TypeScript allows it
- Create/reuse factory functions from `litegraphTestUtils.ts` for mock
objects
- Widen `getWorkflowDataFromFile` return type to include `ComfyMetadata`
directly
- Reduce total `as unknown as` count from ~153 to 71

The remaining 71 occurrences are genuinely necessary due to cross-schema
casts, generic variance, missing index signatures, Float64Array-to-tuple
conversions, and DOM type incompatibilities.

## Test plan

- [x] `pnpm typecheck` passes
- [x] `pnpm lint` passes
- [x] All affected unit tests pass

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9107-fix-replace-as-unknown-as-casts-with-safer-patterns-3106d73d3650815cb5bcd613ad635bd7)
by [Unito](https://www.unito.io)

scripts/collect-i18n-general.ts

@@ -11,7 +11,7 @@ import {
 } from '../packages/shared-frontend-utils/src/formatUtil'
 import { CORE_MENU_COMMANDS } from '../src/constants/coreMenuCommands'
 import { SERVER_CONFIG_ITEMS } from '../src/constants/serverConfig'
-import type { FormItem, SettingParams } from '../src/platform/settings/types'
+import type { SettingParams } from '../src/platform/settings/types'
 import type { ComfyCommandImpl } from '../src/stores/commandStore'
 
 const localePath = './src/locales/en/main.json'
@@ -123,8 +123,8 @@ test('collect-i18n-general', async ({ comfyPage }) => {
     SERVER_CONFIG_ITEMS.map((config) => [
       normalizeI18nKey(config.id),
       {
-        name: (config as unknown as FormItem).name,
-        tooltip: (config as unknown as FormItem).tooltip
+        name: config.name,
+        tooltip: config.tooltip
       }
     ])
   )