deps: react-router-dom 4 -> 6 (history 5, react-router-bootstrap 0.26)

Removes the Router/Switch/Route/Link/LinkContainer legacy-context
warnings. Keeps the shared history singleton (used outside React by
NotificationsObserver + Utils/location) via unstable_HistoryRouter, and
bridges v6 hooks back to v4-shaped history/match/location props with a
new withRouterCompat HOC so the ~20 class pages stay untouched.

- <Switch> -> <Routes>, component= -> element=
- Authenticated/Public -> guard components (children or <Navigate replace>)
- LocationListener -> useLocation + useEffect function
- regex route /fire/:type(active|archive|alert)/:id -> /fire/:type/:id
- history.listen callback is ({ location }) in history v5

Browser-verified: SPA nav, /subscriptions->/login auth redirect,
deep-link /fire/archive/:id (params), browser back/forward. REST smoke
byte-identical.

package.json

@@ -22,7 +22,7 @@
     "google-maps": "^3.2.1",
     "google-maps-image-api-url": "^1.0.3",
     "handlebars": "^4.0.11",
-    "history": "^4.7.2",
+    "history": "^5.3.0",
     "html5-device-mockups": "^3.2.0",
     "i18next": "^23.16.8",
     "i18next-browser-languagedetector": "^8.2.1",
@@ -73,8 +73,8 @@
     "react-places-autocomplete": "^5.4.3",
     "react-progress-bar.js": "^0.2.3",
     "react-resize-detector": "^1.1.0",
-    "react-router-bootstrap": "^0.24.4",
-    "react-router-dom": "^4.2.2",
+    "react-router-bootstrap": "^0.26.3",
+    "react-router-dom": "^6.30.4",
     "react-share": "^2.0.0",
     "simpl-schema": "^1.5.0",
     "simple-line-icons": "^2.4.1",