Make #[slhx::handler] fail when slhx.syms is missing instead of silently skipping generated handle checks. Add compile-fail coverage with an actionable build.rs hint.
req: build/003
req: test/003
Emit handle-form facts from slhx-build and have #[slhx::handler] reject generated form handlers that do not accept slhx::Form<_>. Cover the boundary with compile-fail fixtures.
req: form/004
req: form/006
req: test/003
Make #[slhx::surface] report a compile-time error when slhx.generated.rs is absent instead of silently expanding to an empty module. Add compile-fail coverage for the missing generated include path.
req: build/004
req: test/003
slhx agent