ramus, tangra, flake: apply php backport overlay

Covers every PHP consumer: think/think-backend (php83) on ramus,
wordpress pools (pkgs.php) on tangra, and the perSystem think packages.

flake.nix

@@ -100,6 +100,7 @@
               inherit system;
               overlays = [
                 inputs.self.overlays.packagesOverlay
+                inputs.self.overlays.phpPr576853Overlay # TEMPORARY, see overlays/nixpkgs-pr-576853-php.nix
               ];
               config = { };
             };

machines/ramus/think-greater-chiangmai.nix

@@ -54,7 +54,10 @@ in
     self.nixosModules.think-gtcm
     self.nixosModules.think-backend-gtcm
   ];
-  nixpkgs.overlays = [ self.overlays.packagesOverlay ];
+  nixpkgs.overlays = [
+    self.overlays.packagesOverlay
+    self.overlays.phpPr576853Overlay # TEMPORARY, see overlays/nixpkgs-pr-576853-php.nix
+  ];
 
   clan.core.vars.generators.greaterchiangmai = {
     files = {

machines/tangra/configuration.nix

@@ -1,3 +1,4 @@
+{ self, ... }:
 {
   system.stateVersion = "25.11";
   nixpkgs.hostPlatform = {
@@ -29,4 +30,7 @@
   security.acme.acceptTerms = true;
 
   imports = [ ];
+
+  # TEMPORARY: wordpress php-fpm pools use pkgs.php; see overlays/nixpkgs-pr-576853-php.nix
+  nixpkgs.overlays = [ self.overlays.phpPr576853Overlay ];
 }