fix(delete): run delete hooks and queries in one transaction

- resolvespec/restheadspec: single and batch delete use one transaction
- add sqlmock tests for delete transaction behaviour
- testmodels: serial integer ids; update tests accordingly
- add compose testserver, smoke script, podman-first Makefile targets

docker/Dockerfile.testserver

@@ -0,0 +1,13 @@
+FROM golang:1.25-alpine AS build
+WORKDIR /src
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+RUN CGO_ENABLED=0 go build -o /out/testserver ./cmd/testserver
+
+FROM alpine:3.20
+RUN apk add --no-cache ca-certificates
+COPY --from=build /out/testserver /usr/local/bin/testserver
+COPY docker/testserver.config.yaml /etc/resolvespec/config.yaml
+EXPOSE 8080
+ENTRYPOINT ["testserver"]

docker/testserver.config.yaml

@@ -0,0 +1,95 @@
+# ResolveSpec Test Server Configuration (docker compose, PostgreSQL)
+# This is a minimal configuration for the test server
+
+servers:
+  default_server: "main"
+  shutdown_timeout: 30s
+  drain_timeout: 25s
+  read_timeout: 10s
+  write_timeout: 10s
+  idle_timeout: 120s
+  instances:
+    main:
+      name: "main"
+      host: "0.0.0.0"
+      port: 8080
+      description: "Main server instance"
+      gzip: true
+      tags:
+        env: "test"
+
+logger:
+  dev: true
+  path: ""
+
+cache:
+  provider: "memory"
+
+middleware:
+  rate_limit_rps: 100.0
+  rate_limit_burst: 200
+  max_request_size: 10485760
+
+cors:
+  allowed_origins:
+    - "*"
+  allowed_methods:
+    - "GET"
+    - "POST"
+    - "PUT"
+    - "DELETE"
+    - "OPTIONS"
+  allowed_headers:
+    - "*"
+  max_age: 3600
+
+tracing:
+  enabled: false
+  service_name: "resolvespec"
+  service_version: "1.0.0"
+  endpoint: ""
+
+error_tracking:
+  enabled: false
+  provider: "noop"
+  environment: "development"
+  sample_rate: 1.0
+  traces_sample_rate: 0.1
+
+event_broker:
+  enabled: false
+  provider: "memory"
+  mode: "sync"
+  worker_count: 1
+  buffer_size: 100
+  instance_id: ""
+
+dbmanager:
+  default_connection: "default"
+  max_open_conns: 25
+  max_idle_conns: 5
+  conn_max_lifetime: 30m
+  conn_max_idle_time: 5m
+  retry_attempts: 3
+  retry_delay: 1s
+  health_check_interval: 30s
+  enable_auto_reconnect: true
+  connections:
+    # "default" overrides the built-in default connection (all connections are connected at start)
+    default:
+      name: "default"
+      type: "postgres"
+      host: "postgres-test"
+      port: 5432
+      user: "postgres"
+      password: "postgres"
+      database: "postgres"
+      sslmode: "disable"
+      application_name: "resolvespec-testserver"
+      default_orm: "gorm"
+      enable_logging: true
+      enable_metrics: false
+      connect_timeout: 10s
+      query_timeout: 30s
+
+paths: {}