fix(redact/vite): respect 'forwardRef' and 'classComponents' feature flags

[sukvvon]

The Vite plugin's feature-flag swap was a silent no-op for two flags:
forwardRef: false and classComponents: false. Other flags
(portal, context, suspense, memo, lazy) worked because their
folder names happen to match the ResolvedFeatures key 1:1.

Root cause

features/index.ts imports each feature by its on-disk folder name:

import './forward-ref'
import './class'

The resolveId hook receives the bare specifier (./forward-ref,
./class) and used to cast it directly to keyof ResolvedFeatures:

const name = m[1] as keyof ResolvedFeatures
if (name in features && !features[name]) { ... }

ResolvedFeatures uses camelCase (forwardRef, classComponents), so
'forward-ref' in features and 'class' in features are both false
— the swap branch never ran and the full feature implementation stayed
in the bundle even when the user opted out.

Fix

Introduce an explicit folder → key mapping. The resolve() call still
uses the folder name (it's a disk path), but the feature lookup uses
the mapped camelCase key.

const FOLDER_TO_FEATURE: Record<string, keyof ResolvedFeatures> = {
  portal: 'portal',
  context: 'context',
  suspense: 'suspense',
  memo: 'memo',
  'forward-ref': 'forwardRef',
  lazy: 'lazy',
  class: 'classComponents',
}

Test plan

• New tests/vite-plugin-feature-swap.test.ts — 5 regression cases
  covering both kebab-mapped flags, the five identity-mapped flags,
  the "flag on → no swap" path, and the RSC environment skip
• Reverting the fix makes the forward-ref and class cases fail,
  confirming the test catches the regression
• pnpm --filter tests test — all green
• pnpm test:types — clean