Add dd0c/drift notifications, infra, CI: Slack Block Kit, Dockerfiles, Gitea Actions

- Notification service: Slack Block Kit (remediate/accept buttons), webhook delivery, rate limit handling
- Dispatcher with severity-based channel filtering
- Agent Dockerfile: multi-stage Go build, static binary
- SaaS Dockerfile: multi-stage Node build
- Fly.io config: scale-to-zero, shared-cpu
- Gitea Actions: Go test+vet, Node typecheck+test, cross-compile agent (linux/darwin/windows)

products/02-iac-drift-detection/.gitea/workflows/ci.yml

@@ -0,0 +1,62 @@
+name: CI
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+jobs:
+  agent-test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version: '1.22'
+
+      - name: Test agent
+        run: go test ./...
+        working-directory: products/02-iac-drift-detection/agent
+
+      - name: Vet
+        run: go vet ./...
+        working-directory: products/02-iac-drift-detection/agent
+
+  saas-test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '22'
+
+      - name: Install deps
+        run: npm ci
+        working-directory: products/02-iac-drift-detection/saas
+
+      - name: Type check
+        run: npx tsc --noEmit
+        working-directory: products/02-iac-drift-detection/saas
+
+      - name: Test
+        run: npm test
+        working-directory: products/02-iac-drift-detection/saas
+
+  agent-build:
+    runs-on: ubuntu-latest
+    needs: agent-test
+    if: github.ref == 'refs/heads/main'
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version: '1.22'
+
+      - name: Build agent binaries
+        run: |
+          GOOS=linux GOARCH=amd64 go build -o dist/drift-linux-amd64 ./cmd/drift
+          GOOS=darwin GOARCH=arm64 go build -o dist/drift-darwin-arm64 ./cmd/drift
+          GOOS=windows GOARCH=amd64 go build -o dist/drift-windows-amd64.exe ./cmd/drift
+        working-directory: products/02-iac-drift-detection/agent

products/02-iac-drift-detection/.gitea/workflows/deploy.yml

@@ -0,0 +1,19 @@
+name: Deploy
+on:
+  push:
+    branches: [main]
+    paths: ['products/02-iac-drift-detection/saas/**']
+
+jobs:
+  deploy-saas:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: superfly/flyctl-actions/setup-flyctl@master
+
+      - name: Deploy SaaS to Fly.io
+        run: flyctl deploy --config fly.toml --remote-only
+        working-directory: products/02-iac-drift-detection/saas
+        env:
+          FLY_API_TOKEN: ${{ secrets.FLY_API_TOKEN }}