ci: harden woodpecker backend step

.woodpecker.yml

@@ -1,14 +1,29 @@
 steps:
   backend:
-    image: rust:1.76-bookworm
+    image: rust:1.93-bookworm
     environment:
       DATABASE_URL: postgres://postgres:postgres@postgres:5432/likwid_ci
       RUST_BACKTRACE: 1
     commands:
       - rustup component add rustfmt clippy
-      - cargo install -j 2 sqlx-cli --no-default-features --features postgres,tls-rustls
+      - cargo install -j 2 sqlx-cli --version 0.8.6 --locked --no-default-features --features postgres,tls-rustls
       - cd backend
-      - sqlx migrate run
+      - |
+        ok=0
+        i=1
+        while [ "$i" -le 30 ]; do
+          if sqlx migrate run; then
+            ok=1
+            break
+          fi
+          echo "sqlx migrate run failed (attempt ${i}/30); waiting for postgres..."
+          sleep 1
+          i=$((i + 1))
+        done
+        if [ "$ok" -ne 1 ]; then
+          echo "sqlx migrate run failed after 30 attempts"
+          exit 1
+        fi
       - cargo fmt --all -- --check
       - cargo clippy -j 2 --all-targets --all-features -- -D warnings
       - cargo test -j 2 --all