add initial Go implementation of arcline-audit

Implements the full site health auditor with four check groups:

  - SSL/TLS (certificate validity, expiry, chain, TLS version, ciphers)

  - HTTP (redirect chain, security headers, response time)

  - DNS (A/AAAA, MX, SPF, DKIM, DMARC, DNSSEC)

  - Infrastructure (CDN detection, common port probes)

Includes CLI with --checks filter, --json and --out flags,

cross-compile Makefile, and GitLab CI pipeline.

Signed-off-by: Blake Ridgway <blake@blakeridgway.com>

.gitlab-ci.yml

@@ -0,0 +1,57 @@
+stages:
+  - test
+  - build
+  - release
+
+.test_template: &test
+  stage: test
+  image: golang:1.22-alpine
+  script:
+    - go vet ./...
+    - go build -o /dev/null ./cmd/arcline-audit/
+
+test:linux:
+  <<: *test
+
+.build_template: &build
+  stage: build
+  image: golang:1.22-alpine
+  script:
+    - apk add --no-cache make
+    - make ${TARGET}
+  artifacts:
+    paths:
+      - arcline-audit-*
+    expire_in: 30 days
+
+build:linux:
+  <<: *build
+  variables:
+    TARGET: linux
+
+build:darwin:
+  <<: *build
+  variables:
+    TARGET: darwin
+
+build:windows:
+  <<: *build
+  variables:
+    TARGET: windows
+
+release:
+  stage: release
+  image: golang:1.22-alpine
+  script:
+    - apk add --no-cache make
+    - make release
+    - echo "Release artifacts: arcline-audit-*"
+  artifacts:
+    paths:
+      - arcline-audit-linux-amd64
+      - arcline-audit-darwin-amd64
+      - arcline-audit-windows-amd64.exe
+    expire_in: 90 days
+  only:
+    - tags
+