refactor: introduce PageHeader component (#6629)

* refactor: introduce PageHeader component

* feat: split up according to component structure guide

* fix: lint

* fix: label inconsistencies

* feat: refactor PageHeader (again)

* refactor: old impls

* fix: changes

* fix: rescan

* fix: prepr

* fix: dedupe

* fix: rev

* fix: lint

* fix: lint

---------

Co-authored-by: Prospector <6166773+Prospector@users.noreply.github.com>

apps/frontend/src/locales/ja-JP/index.json

@@ -2597,9 +2597,6 @@
   "profile.label.collection": {
     "message": "コレクション"
   },
-  "profile.label.downloads": {
-    "message": "{count}件のダウンロード"
-  },
   "profile.label.joined": {
     "message": "参加: "
   },
@@ -2618,9 +2615,6 @@
   "profile.label.organizations": {
     "message": "組織"
   },
-  "profile.label.projects": {
-    "message": "{count} {countPlural, plural, one {プロジェクト} other {プロジェクト}}"
-  },
   "profile.label.saving": {
     "message": "保存中…"
   },