Initial commit: full Phases 1-6 implementation

Post-repair hardware validation pipeline for Proxmox cluster hosts.
Go orchestrator + in-image agent + mkosi live image + bundled dnsmasq
PXE + SQLite + HTMX/SSE UI + notify registry + janitor + full docs.

.github/workflows/ci.yml

@@ -0,0 +1,45 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+permissions:
+  contents: read
+
+jobs:
+  lint-and-test:
+    name: Lint + build + test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: "1.26.x"
+          cache: true
+
+      - name: Install templ
+        run: go install github.com/a-h/templ/cmd/templ@v0.3.1001
+
+      - name: Generate templ
+        run: templ generate
+
+      - name: Verify go.mod + go.sum are tidy
+        run: |
+          go mod tidy
+          git diff --exit-code go.mod go.sum
+
+      - name: Vet
+        run: go vet ./...
+
+      - name: Build (host)
+        run: |
+          go build ./...
+          GOOS=linux GOARCH=amd64 go build ./...
+
+      - name: Test
+        run: go test -race -count=1 ./...