fix: resolve Gitea Actions authentication issue in nix-update workflow

- Replace actions/checkout@v4 with manual git clone using token-embedded
  URL to fix 'could not read Username: terminal prompts disabled' error
- Disable GIT_TERMINAL_PROMPT and GIT_ASKPASS to prevent interactive prompts
- Consolidate git config setup into checkout step

Package updates:
- beads: 0.47.1 -> 0.47.2
- opencode: 1.1.18 -> 1.1.25

Beads state sync:
- Close nixpkgs-8jw (Gitea Actions node PATH issue resolved)
- Close nixpkgs-r3u (Gitea Actions nix-update workflow complete)
- Create nixpkgs-8ng (opencode subpackage update requires special args)
- Remove deleted tombstone issues

pkgs/opencode/default.nix

@@ -13,12 +13,12 @@
   writableTmpDirAsHomeHook,
 }: let
   pname = "opencode";
-  version = "1.1.18";
+  version = "1.1.25";
   src = fetchFromGitHub {
     owner = "anomalyco";
     repo = "opencode";
     tag = "v${version}";
-    hash = "sha256-3A4s0FpjZuGB0HGMQVBXfWq+0yHmeIvnEQTSX3amV4I=";
+    hash = "sha256-aF+4LL0x9wU2Ktrv/nJE2VXgUeXFrwJ16pa1sGNhpi4=";
   };
 
   node_modules = stdenvNoCC.mkDerivation {
@@ -66,7 +66,7 @@
     # NOTE: Required else we get errors that our fixed-output derivation references store paths
     dontFixup = true;
 
-    outputHash = "sha256-zSco4ORQQOqV3vMPuP+M/q/hBa+MJGnTKIlxgngMA3g=";
+    outputHash = "sha256-qheQCN71VM3M35+j9XhaCdxQNo5ze8mV8sDFaX0WVWM=";
     outputHashAlgo = "sha256";
     outputHashMode = "recursive";
   };