fix(core): drop the unused optional @angular/platform-server peer (#3792)

npm 10, and npm 11 before 11.20, resolve a missing optional peer anyway
while installing. For an app whose package.json uses caret ranges and
whose Angular is one patch behind the newest, npm picks the newest
@angular/platform-server, which requires that exact newest
@angular/core, and the install stops with ERESOLVE. Every current Node
line bundles one of those npm versions.

Nothing in the published package imports @angular/platform-server, so
the peer is removed. Apps that render on the server still install it
themselves, as they already do.

(cherry picked from commit bbce8f0)

Author: armando-navarro

src/package.json

@@ -30,13 +30,11 @@
     "@angular/common": "^20.0.0",
     "@angular/core": "^20.0.0",
     "@angular/platform-browser": "^20.0.0",
-    "@angular/platform-server": "^20.0.0",
     "rxjs": "~7.8.0",
     "firebase-tools": "^14.0.0 || ^15.0.0"
   },
   "peerDependenciesMeta": {
-    "firebase-tools": { "optional": true },
-    "@angular/platform-server": { "optional": true }
+    "firebase-tools": { "optional": true }
   },
   "dependencies": {
     "firebase": "^11.8.0",