Fix: Docker build args injection regex to support service names

The regex pattern in injectDockerComposeBuildArgs() was too restrictive
and failed to match `docker compose build servicename` commands. Changed
the lookahead from `(?=\s+(?:--|-)|\s+(?:&&|\|\||;|\|)|$)` to the
simpler `(?=\s|$)` to allow any content after the build command,
including service names with hyphens/underscores and flags.

Also improved the ApplicationDeploymentJob to use the new helper function
and added comprehensive test coverage for service-specific builds.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

bootstrap/helpers/docker.php

@@ -1376,3 +1376,62 @@ function injectDockerComposeFlags(string $command, string $composeFilePath, stri
     // Replace only first occurrence to avoid modifying comments/strings/chained commands
     return preg_replace('/docker\s+compose/', $dockerComposeReplacement, $command, 1);
 }
+
+/**
+ * Inject build arguments right after build-related subcommands in docker/docker compose commands.
+ * This ensures build args are only applied to build operations, not to push, pull, up, etc.
+ *
+ * Supports:
+ * - docker compose build
+ * - docker buildx build
+ * - docker builder build
+ * - docker build (legacy)
+ *
+ * Examples:
+ * - Input:  "docker compose -f file.yml build"
+ *   Output: "docker compose -f file.yml build --build-arg X --build-arg Y"
+ *
+ * - Input:  "docker buildx build --platform linux/amd64"
+ *   Output: "docker buildx build --build-arg X --build-arg Y --platform linux/amd64"
+ *
+ * - Input:  "docker builder build --tag myimage:latest"
+ *   Output: "docker builder build --build-arg X --build-arg Y --tag myimage:latest"
+ *
+ * - Input:  "docker compose build && docker compose push"
+ *   Output: "docker compose build --build-arg X --build-arg Y && docker compose push"
+ *
+ * - Input:  "docker compose push"
+ *   Output: "docker compose push" (unchanged - no build command found)
+ *
+ * @param  string  $command  The docker command
+ * @param  string  $buildArgsString  The build arguments to inject (e.g., "--build-arg X --build-arg Y")
+ * @return string The modified command with build args injected after build subcommand
+ */
+function injectDockerComposeBuildArgs(string $command, string $buildArgsString): string
+{
+    // Early return if no build args to inject
+    if (empty(trim($buildArgsString))) {
+        return $command;
+    }
+
+    // Match build-related commands:
+    // - ' builder build' (docker builder build)
+    // - ' buildx build' (docker buildx build)
+    // - ' build' (docker compose build, docker build)
+    // Followed by either:
+    // - whitespace (allowing service names, flags, or any valid arguments)
+    // - end of string ($)
+    // This regex ensures we match build subcommands, not "build" in other contexts
+    // IMPORTANT: Order matters - check longer patterns first (builder build, buildx build) before ' build'
+    $pattern = '/( builder build| buildx build| build)(?=\s|$)/';
+
+    // Replace the first occurrence of build command with build command + build-args
+    $modifiedCommand = preg_replace(
+        $pattern,
+        '$1 '.$buildArgsString,
+        $command,
+        1  // Only replace first occurrence
+    );
+
+    return $modifiedCommand ?? $command;
+}