feat: define module database access

Introduce ModuleDatabase (a typed, restricted Drizzle query surface) and the frozen
ModuleRuntimeServices boundary in @ekklesia/contracts, and thread the same services object
through Core's module start/stop lifecycle hooks and apps/api's authorized module HTTP handler
context. apps/api builds the facade via a new core/src/modules/database.ts view (createModuleDatabaseView)
over the one existing shared PostgreSQL pool, alongside the identity and authorization views, and
wires it into startApi's fixed startup order ahead of Identity/Authorization construction.
Registration stays database-free; a module reaches its database only through an authorized start,
stop, or HTTP handler invocation.

packages/contracts/src/index.ts

@@ -1,6 +1,7 @@
 export * from "./authorization.js";
 export * from "./identifiers.js";
 export * from "./identity.js";
+export * from "./module-database.js";
 export * from "./module-http.js";
 export * from "./module-lifecycle.js";
 export * from "./module-manifest.js";