fix: resolve i18n no-restricted-imports lint warnings (#8704)

## Summary

Fix all i18n `no-restricted-imports` lint warnings and upgrade rules
from `warn` to `error`.

## Changes

- **What**: Migrate Vue components from `import { t/d } from '@/i18n'`
to `const { t } = useI18n()`. Migrate non-component `.ts` files from
`useI18n()` to `import { t/d } from '@/i18n'`. Allow `st` import from
`@/i18n` in Vue components (it wraps `te`/`t` for safe fallback
translation). Remove `@deprecated` tag from `i18n.ts` global exports
(still used by `st` and non-component code). Upgrade both lint rules
from `warn` to `error`.

## Review Focus

- The `st` helper is intentionally excluded from the Vue component
restriction since it provides safe fallback translation needed for
custom node definitions.

Fixes #8701

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8704-fix-resolve-i18n-no-restricted-imports-lint-warnings-2ff6d73d365081ae84d8eb0dfef24323)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Amp <amp@ampcode.com>

eslint.config.ts

@@ -287,12 +287,12 @@ export default defineConfig([
     files: ['**/*.vue'],
     rules: {
       'no-restricted-imports': [
-        'warn',
+        'error',
         {
           paths: [
             {
               name: '@/i18n',
-              importNames: ['t', 'd', 'st', 'te'],
+              importNames: ['t', 'd', 'te'],
               message:
                 "In Vue components, use `const { t } = useI18n()` instead of importing from '@/i18n'."
             }
@@ -301,13 +301,13 @@ export default defineConfig([
       ]
     }
   },
-  // Non-composable .ts files must use the global t/d/st/te, not useI18n()
+  // Non-composable .ts files must use the global t/d/te, not useI18n()
   {
     files: ['**/*.ts'],
     ignores: ['**/use[A-Z]*.ts', '**/*.test.ts', 'src/i18n.ts'],
     rules: {
       'no-restricted-imports': [
-        'warn',
+        'error',
         {
           paths: [
             {