fix(dagger): pin all references to v0.20.8 (the engine actually running)

CI on the previous commit failed because the runner CLI and remote engine
are both still v0.20.8 ("module requires dagger v0.21.4, but you have
v0.20.8").  The issue offered two paths — bump everything to v0.21.4, or
re-pin the CLI — so take the second: align ci/dagger.json, flake.nix,
.forgejo/Dockerfile and DAGGER.md back to v0.20.8.  The check script
remains and now enforces lockstep at the new baseline; once the host
engine and runner image are upgraded, a single follow-up bumps all four
references together.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.forgejo/Dockerfile

@@ -18,7 +18,7 @@ RUN curl -fsSL -o /usr/local/bin/sops https://github.com/getsops/sops/releases/d
 
 # Dagger CLI — pinned to match the engine version on the runner host
 RUN curl -fsSL https://dl.dagger.io/dagger/install.sh \
-    | DAGGER_VERSION=0.21.4 BIN_DIR=/usr/local/bin sh
+    | DAGGER_VERSION=0.20.8 BIN_DIR=/usr/local/bin sh
 
 # Task runner
 RUN curl -fsSL https://taskfile.dev/install.sh \

DAGGER.md

@@ -39,7 +39,7 @@ WorkingDirectory=/home/dagger-svc
 # Replace 1003 with the actual UID of dagger-svc
 Environment=DOCKER_HOST=unix:///run/user/1003/podman/podman.sock
 Environment=XDG_RUNTIME_DIR=/run/user/1003
-ExecStart=/usr/bin/nix run github:dagger/nix/v0.21.4#dagger -- engine --addr tcp://0.0.0.0:8080
+ExecStart=/usr/bin/nix run github:dagger/nix/v0.20.8#dagger -- engine --addr tcp://0.0.0.0:8080
 Restart=always
 
 [Install]

ci/dagger.json

@@ -1,6 +1,6 @@
 {
   "name": "ci",
-  "engineVersion": "v0.21.4",
+  "engineVersion": "v0.20.8",
   "sdk": {
     "source": "go"
   }

flake.nix

@@ -53,12 +53,12 @@
         # fetch the CLI binary directly.  Keep this version in lockstep with
         # ci/dagger.json (engineVersion) and .forgejo/Dockerfile (DAGGER_VERSION) —
         # scripts/check_dagger_versions.sh enforces this.
-        dagger021 = pkgs.stdenv.mkDerivation {
+        daggerCli = pkgs.stdenv.mkDerivation {
           pname = "dagger";
-          version = "0.21.4";
+          version = "0.20.8";
           src = pkgs.fetchurl {
-            url = "https://dl.dagger.io/dagger/releases/0.21.4/dagger_v0.21.4_linux_amd64.tar.gz";
-            sha256 = "0wlnbr4g5069755131yjp2a6alacn64f1c8b27xn0cbynq3zicjd";
+            url = "https://dl.dagger.io/dagger/releases/0.20.8/dagger_v0.20.8_linux_amd64.tar.gz";
+            sha256 = "1ns6wq2z1skd2fq9lbrcali0s8kn24p3haamnjjgchg6zlv6b960";
           };
           sourceRoot = ".";
           installPhase = ''
@@ -71,7 +71,7 @@
         devShells.default = pkgs.mkShell {
           buildInputs = with pkgs; [
             # Dagger CLI
-            dagger021
+            daggerCli
 
             # Go compiler — for Dagger development
             go