refactor(api)!: align client with canonical HTTP contract

Route all feature requests through business API modules, sync generated DTOs, and add communication tests and architecture documentation.

BREAKING CHANGE: migrate the client to plural resource paths, canonical snake_case fields, ISO timestamps, and explicit paginated responses.

scripts/test-resolver.mjs

@@ -0,0 +1,16 @@
+import { registerHooks } from 'node:module'
+import { existsSync } from 'node:fs'
+
+const source = new URL('../src/', import.meta.url)
+registerHooks({
+    resolve(specifier, context, nextResolve) {
+        if (specifier.startsWith('@/')) {
+            return nextResolve(new URL(`${specifier.slice(2)}.ts`, source).href, context)
+        }
+        if (specifier.startsWith('.') && context.parentURL?.startsWith(source.href)) {
+            const candidate = new URL(`${specifier}.ts`, context.parentURL)
+            if (existsSync(candidate)) return nextResolve(candidate.href, context)
+        }
+        return nextResolve(specifier, context)
+    },
+})