ci: harden checks before Blacksmith migration

.github/dependabot.yml

@@ -0,0 +1,33 @@
+version: 2
+
+updates:
+  - package-ecosystem: gomod
+    directory: /
+    schedule:
+      interval: weekly
+      day: monday
+    open-pull-requests-limit: 5
+    labels:
+      - dependencies
+      - go
+    commit-message:
+      prefix: "chore(deps)"
+      include: scope
+    groups:
+      charmbracelet:
+        patterns:
+          - "github.com/charmbracelet/*"
+          - "charm.land/*"
+
+  - package-ecosystem: github-actions
+    directory: /
+    schedule:
+      interval: weekly
+      day: monday
+    open-pull-requests-limit: 5
+    labels:
+      - dependencies
+      - ci
+    commit-message:
+      prefix: "chore(ci)"
+      include: scope

.github/rulesets/main-protection.json

@@ -0,0 +1,43 @@
+{
+  "name": "main branch protection",
+  "target": "branch",
+  "enforcement": "active",
+  "conditions": {
+    "ref_name": {
+      "include": ["~DEFAULT_BRANCH"],
+      "exclude": []
+    }
+  },
+  "rules": [
+    { "type": "deletion" },
+    { "type": "non_fast_forward" },
+    {
+      "type": "pull_request",
+      "parameters": {
+        "required_approving_review_count": 0,
+        "dismiss_stale_reviews_on_push": false,
+        "require_code_owner_review": false,
+        "require_last_push_approval": false,
+        "required_review_thread_resolution": false,
+        "allowed_merge_methods": ["merge", "squash"]
+      }
+    },
+    {
+      "type": "required_status_checks",
+      "parameters": {
+        "strict_required_status_checks_policy": true,
+        "do_not_enforce_on_create": false,
+        "required_status_checks": [
+          { "context": "Test (ubuntu-latest)" },
+          { "context": "Test (macos-latest)" },
+          { "context": "Test (windows-latest)" },
+          { "context": "Mod Tidy Drift" },
+          { "context": "GoReleaser Config" },
+          { "context": "Lint" },
+          { "context": "Analyze (go)" }
+        ]
+      }
+    }
+  ],
+  "bypass_actors": []
+}

.github/workflows/ci.yml

@@ -13,8 +13,15 @@ permissions:
 
 jobs:
   test:
-    name: Test
-    runs-on: ubuntu-latest
+    name: Test (${{ matrix.os }})
+    strategy:
+      fail-fast: false
+      matrix:
+        os:
+          - ubuntu-latest
+          - macos-latest
+          - windows-latest
+    runs-on: ${{ matrix.os }}
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -34,16 +41,14 @@ jobs:
       - name: Test
         run: go test -race -v ./...
 
-  build-matrix:
-    name: Build (${{ matrix.os }})
-    runs-on: ${{ matrix.os }}
-    strategy:
-      fail-fast: false
-      matrix:
-        os:
-          - ubuntu-latest
-          - macos-latest
-          - windows-latest
+      - name: Build
+        env:
+          CGO_ENABLED: "0"
+        run: go build ./...
+
+  mod-tidy:
+    name: Mod Tidy Drift
+    runs-on: ubuntu-latest
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -54,10 +59,35 @@ jobs:
           go-version-file: go.mod
           cache: true
 
-      - name: Build
-        env:
-          CGO_ENABLED: "0"
-        run: go build ./...
+      - name: Tidy
+        run: go mod tidy
+
+      - name: Verify no drift
+        run: |
+          git diff --exit-code go.mod go.sum || {
+            echo "::error::go.mod or go.sum is out of sync. Run 'go mod tidy' locally and commit the result."
+            exit 1
+          }
+
+  goreleaser-check:
+    name: GoReleaser Config
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Go
+        uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+          cache: false
+
+      - name: Validate .goreleaser.yml
+        uses: goreleaser/goreleaser-action@v6
+        with:
+          distribution: goreleaser
+          version: "~> v2"
+          args: check
 
   lint:
     name: Lint