feat: define module HTTP routes

Phase 5B, pass 1: framework-neutral module HTTP route contracts and runtime
registration. Adds @ekklesia/contracts' module-http.ts (methods, canonical
path grammar, route definition/context/handler types, and validation)
and Core's module runtime staging/publication of a module's declared
routes alongside its capabilities, gated on the module's own manifest
permissions. Routes are collected into StartedModuleRuntime as an
immutable snapshot but are not yet mounted into apps/api; that is pass 2.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

packages/contracts/src/module-runtime.ts

@@ -1,5 +1,6 @@
 import type { CapabilityId, ModuleId } from "./identifiers.js";
 import { moduleIdSchema } from "./identifiers.js";
+import type { ModuleHttpRouteRegistrar } from "./module-http.js";
 import { semanticVersionSchema } from "./versions.js";
 
 export type Awaitable<Value> = Value | PromiseLike<Value>;
@@ -21,6 +22,10 @@ export interface CapabilityRegistrar extends CapabilityResolver {
 
 export interface ModuleRegistrationContext {
   readonly capabilities: CapabilityRegistrar;
+  /** Available only during `register` — never on `ModuleRuntimeContext` — so a route can only ever
+   * be declared while Core is still building the immutable startup snapshot, never added or removed
+   * afterward from `start`, `stop`, or any other post-registration code path. */
+  readonly http: ModuleHttpRouteRegistrar;
   readonly moduleId: ModuleId;
 }