CI matrix for two lines: .NET 10 and 11 SDKs, PostgreSQL floor and 18 legs per line #152

The integration suite runs one image, postgres:17-alpine (ContainerLifecycle.cs), on both the integration project and the infinity-disabled one. The 10.x line documents PostgreSQL 14+ (multirange) and nothing tests 14; the 11.x line's floor is 16 (Npgsql EF 11 raises the default compatibility target from 14 to 16, accepted 2026-10-18) and nothing tests 16. Temporal constraints need 18 on either line.

• The container image comes from an environment variable with the floor as the default per branch; CI runs a floor leg and an 18 leg: 14 + 18 on main/release/10.x, 16 + 18 on net11/the 11 main.

• actions/setup-dotnet installs the .NET 11 RC SDK on the 11 line (prerelease), the .NET 10 SDK on the 10 line; the consumer smoke test, including the NativeAOT consumer, runs with the line's SDK.

• CI=true keeps the live layer mandatory on every leg.

• The oracle pg-surface listing is regenerated from the floor image of each line so postgres-surface.json names the floor's catalogue.

• Dependabot targets only the default branch. .github/dependabot.yml needs a target-branch: release/10.x copy of the github-actions entry (SHA-pinned actions on the LTS branch age otherwise) and of the nuget test-project entry; while net11 exists it needs the same. Keep the src/ exclusion on both.

Done when both legs are green on both lines and the floor is stated once, in the docs, from the same variable the workflow reads.