ci: migrate to Gitea Actions + publish release bundle to package registry

Adds `.gitea/workflows/{ci,e2e,release}.yml` and removes the old
`.github/workflows/` counterparts. Gitea reads both paths, so keeping
them would double-run every job on every push.

- ci.yml / e2e.yml are 1:1 ports of the GitHub versions, just with
  `runs-on: self-hosted` (Gitea has no hosted runners).
- release.yml is new: fires on push to main, runs `make release`, then
  publishes `vetting-bundle.tar.gz` to the Gitea generic package
  registry under two versions — `sha-<short-sha>` (immutable, pinnable)
  and `latest` (rolling alias, DELETE+PUT on each run). Auth via a
  REGISTRY_TOKEN secret + REGISTRY_URL variable configured on the Gitea
  side.

The runner is being reconfigured to privileged so `mkosi` + `debootstrap`
can build the live image inside CI.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.gitea/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: self-hosted
+    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 ./...