[Website] locale-segment routing and shared Lingui factory (#20079)

**1. Shared Lingui factory in `twenty-shared`**

- Extracted `createI18nInstanceFactory` into
`packages/twenty-shared/src/i18n/create-i18n-instance-factory.ts` so
every package gets the same per-render Lingui bootstrap with a
per-locale singleton cache and a `SOURCE_LOCALE` fallback.
- `twenty-emails/src/utils/i18n.utils.ts` now consumes the shared
factory.

**2. `twenty-website-new` Lingui bootstrap + Crowdin wiring**

- `lingui.config.ts`, `src/lib/i18n/*`, `nx run
twenty-website-new:lingui:{extract,compile}`.
- 31 locale PO files generated; minified compiled output kept out of
Prettier and Oxlint.
- `i18n-{push,pull}.yaml` workflows updated to include
`twenty-website-new` in Crowdin sync.

**3. `app/[locale]/...` segment routing with English at the root**

- All marketing routes moved under `src/app/[locale]/`; static
generation preserved (15 routes × 31 locales = 465 prerendered URLs).
- Middleware behavior:
  - `/{en}/...`         → 301 redirect to unprefixed canonical.
  - `/{non-en}/...`     → pass through, set `NEXT_LOCALE` cookie.

### What this PR explicitly does not do (deferred)

- Lingui-wrapping the actual marketing copy. Keys, build pipeline, and
  runtime are wired; copy migration is a separate, reviewer-friendlier
  PR.

.github/workflows/i18n-pull.yaml

@@ -58,6 +58,7 @@ jobs:
           npx nx run twenty-server:lingui:compile --strict
           npx nx run twenty-emails:lingui:compile --strict
           npx nx run twenty-front:lingui:compile --strict
+          npx nx run twenty-website-new:lingui:compile --strict
         continue-on-error: true
 
       - name: Stash any changes before pulling translations
@@ -115,6 +116,7 @@ jobs:
           npx nx run twenty-server:lingui:compile
           npx nx run twenty-emails:lingui:compile
           npx nx run twenty-front:lingui:compile
+          npx nx run twenty-website-new:lingui:compile
           git status
           git add .
           if ! git diff --staged --quiet --exit-code; then

.github/workflows/i18n-push.yaml

@@ -41,6 +41,7 @@ jobs:
           npx nx run twenty-server:lingui:extract
           npx nx run twenty-emails:lingui:extract
           npx nx run twenty-front:lingui:extract
+          npx nx run twenty-website-new:lingui:extract
 
       - name: Check and commit extracted files
         id: check_extract_changes
@@ -60,6 +61,7 @@ jobs:
           npx nx run twenty-server:lingui:compile
           npx nx run twenty-emails:lingui:compile
           npx nx run twenty-front:lingui:compile
+          npx nx run twenty-website-new:lingui:compile
 
       - name: Check and commit compiled files
         id: check_compile_changes