fix(core): raise the rxfire floor to ^6.2.0 for its firebase 12 peers

rxfire 6.1.0 peers firebase ^9||^10||^11, so npm installs a second
firebase 11 next to @angular/fire's firebase 12 and the first Firestore
read throws "Type does not match the expected instance". rxfire 6.2.0
(the peer-range fix, rxfire#152) is on npm latest since 2026-07-22.

^6.1.0 already resolves to 6.2.0 on fresh installs; the raised floor is
for upgraders whose lockfile pins rxfire 6.1.0, which survives an
@angular/fire upgrade and recreates the dual-SDK tree. ^6.2.0 forces
the bump.

Also drop the root overrides block that forced rxfire's firebase peer
to ^12.4.0 in this repo's own tree (obsolete with 6.2.0), and sync the
lockfile's stale root version 21.0.0-next.0 to 21.0.0-rc.0 to match
package.json.

Author: armando-navarro

package-lock.json

@@ -66,7 +66,7 @@
     "jsonc-parser": "^3.0.0",
     "open": "^7.0.3 || ^8.0.0",
     "ora": "^5.3.0",
-    "rxfire": "^6.1.0",
+    "rxfire": "^6.2.0",
     "rxjs": "~7.8.0",
     "semver": "^7.1.3",
     "triple-beam": "^1.3.0",
@@ -120,10 +120,5 @@
     "typescript": ">=5.9 <6.0",
     "yaml": "^2.7.0"
   },
-  "overrides": {
-    "rxfire": {
-      "firebase": "^12.4.0"
-    }
-  },
   "typings": "index.d.ts"
 }

package.json

@@ -36,7 +36,7 @@
   },
   "dependencies": {
     "firebase": "^12.4.0",
-    "rxfire": "^6.1.0",
+    "rxfire": "^6.2.0",
     "@angular-devkit/schematics": "^21.0.0",
     "@schematics/angular": "^21.0.0",
     "tslib": "^2.3.0"