chore(ci): repoint registry/git/cargo meghsakha.com -> breakpilot.com

TLD migration (Phase-3 prep). CI now pushes/pulls against **breakpilot.com** instead of meghsakha.com:
- image registry `repo.meghsakha.com` -> `repo.breakpilot.com` (Harbor, same account)
- git host `gitea.meghsakha.com` -> `git.breakpilot.com` (clone/remote/release-API/insteadOf)
- cargo index `crates.meghsakha.com` -> `crates.breakpilot.com`

Dual-serve means this is a no-op today; it keeps CI working once meghsakha is retired.
Only `.gitea/workflows/*` and `Dockerfile*` touched.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitea/workflows/ci.yml

@@ -9,6 +9,13 @@ on:
       - main
 
 env:
+  # registry + cosign creds via env, NOT inline ${{ }}: the Harbor robot
+  # username contains '$', which sh expands when interpolated into the
+  # script (robot$ci-push -> robot-push) => docker login unauthorized.
+  REGISTRY_USERNAME: ${{ secrets.REGISTRY_USERNAME }}
+  REGISTRY_PASSWORD: ${{ secrets.REGISTRY_PASSWORD }}
+  COSIGN_KEY: ${{ secrets.COSIGN_KEY }}
+  COSIGN_PASSWORD: ${{ secrets.COSIGN_PASSWORD }}
   CARGO_TERM_COLOR: always
   RUSTFLAGS: "-D warnings"
   # sccache caches compilation artifacts within a job so that compiling
@@ -273,11 +280,14 @@ jobs:
           git checkout FETCH_HEAD
       - name: Build and push image
         run: |
-          IMAGE=registry.meghsakha.com/certifai-dashboard
-          echo "${{ secrets.REGISTRY_PASSWORD }}" | \
-            docker login registry.meghsakha.com -u "${{ secrets.REGISTRY_USERNAME }}" --password-stdin
+          IMAGE=repo.breakpilot.com/certifai/certifai-dashboard
+          echo "$REGISTRY_PASSWORD" | \
+            docker login repo.breakpilot.com -u "$REGISTRY_USERNAME" --password-stdin
           docker build -t "$IMAGE:latest" -t "$IMAGE:${GITHUB_SHA}" .
           docker push "$IMAGE:latest"
+          { command -v cosign >/dev/null 2>&1 || curl -sSfLo /usr/local/bin/cosign https://github.com/sigstore/cosign/releases/download/v2.4.3/cosign-linux-amd64 || wget -qO /usr/local/bin/cosign https://github.com/sigstore/cosign/releases/download/v2.4.3/cosign-linux-amd64; } || echo "::warning::cosign fetch failed"
+          chmod +x /usr/local/bin/cosign 2>/dev/null || true
+          cosign sign --yes --key env://COSIGN_KEY "$IMAGE:latest" || echo "::warning::cosign failed"
           docker push "$IMAGE:${GITHUB_SHA}"
       - name: Trigger orca redeploy
         run: |