DEVX-83: fix: fail lint-dockerfiles when hadolint is missing

src/devx/tools/install_tools.py

@@ -6,6 +6,7 @@ Handles installation of:
 - git-cliff (changelog generator)
 - act_runner (Gitea Actions local runner, optional)
 - tea (Gitea CLI — official command-line tool for Gitea API operations)
+- hadolint (Dockerfile linter)
 
 Each tool is installed to ``~/.local/bin`` if not already on PATH.
 Idempotent: skips tools that are already available.
@@ -39,6 +40,8 @@ ACT_RUNNER_VERSION = "0.2.11"
 
 TEA_VERSION = "0.14.1"
 
+HADOLINT_VERSION = "2.12.0"
+
 
 def _arch() -> str:
     """Return the architecture string used by release assets."""
@@ -161,7 +164,20 @@ def install_tea() -> bool:
     return True
 
 
-TOOL_NAMES = ["actionlint", "git-cliff", "act_runner", "tea"]
+def install_hadolint() -> bool:
+    """Install hadolint if not already present. Returns True if installed/skipped."""
+    if _is_installed("hadolint"):
+        click.echo("hadolint: already installed")
+        return True
+    machine = platform.machine().lower()
+    arch = "x86_64" if machine in {"x86_64", "amd64"} else "arm64"
+    url = f"https://github.com/hadolint/hadolint/releases/download/v{HADOLINT_VERSION}/hadolint-Linux-{arch}"
+    dest = _download_binary(url, "hadolint")
+    click.echo(f"hadolint: installed to {dest}")
+    return True
+
+
+TOOL_NAMES = ["actionlint", "git-cliff", "act_runner", "tea", "hadolint"]
 
 
 def _install_tool(name: str) -> bool:
@@ -174,6 +190,8 @@ def _install_tool(name: str) -> bool:
         return install_act_runner()
     if name == "tea":
         return install_tea()
+    if name == "hadolint":
+        return install_hadolint()
     raise click.ClickException(f"Unknown tool: {name}")