Manual how-to: serve your schema over HTTP (the GraphitronApplication SPI adapter)

The manual documents the GraphitronApplication SPI adapter shape nowhere: the tutorial boots the sakila example and curls /graphql without ever showing the wiring, and AbstractGraphitronApplication appears in docs/manual/ only incidentally (how-to/tenant-scoping.adoc). The only consumer-facing "how do I serve my schema over HTTP" recipe is graphitron-sakila-example/README.md’s app section, a per-module README the docs system does not treat as a primary surface; that positioning gap is why the section kept drifting (R416, R417). Write a manual how-to ("Serve your schema over HTTP") covering the SPI seam: implement `GraphitronApplication (or extend AbstractGraphitronApplication), supply the schema over the generated facade, build the engine on the owned-connection path via Graphitron.runtime(dataSource, dialect), produce per-request execution input (with the real claims-payload derivation, not the example’s hard-coded placeholder), and depend on graphitron-jakarta-rest plus a JSON-B provider. ManualXrefIntegrityTest already guards manual xrefs, the tutorial can point at it, and the example README’s app section can shrink to a pointer plus the adapter link. Surfaced by the R417 Spec-time principles-architect consult.