Contract-first API with DTOs, validation, and server-side OpenAPI post-processing

Add dedicated request/response DTOs for all controllers, replacing raw
JsonNode parameters with validated types. Move OpenAPI path-prefix stripping
and ProcessorNode children injection into OpenApiCustomizer beans so the
spec served at /api/v1/api-docs is already clean — eliminating the need for
the ui/scripts/process-openapi.mjs post-processing script.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cameleer3-server-app/src/test/java/com/cameleer3/server/app/controller/AgentRegistrationControllerIT.java

@@ -139,7 +139,7 @@ class AgentRegistrationControllerIT extends AbstractClickHouseIT {
         JsonNode body = objectMapper.readTree(response.getBody());
         assertThat(body.isArray()).isTrue();
         for (JsonNode agent : body) {
-            assertThat(agent.get("state").asText()).isEqualTo("LIVE");
+            assertThat(agent.get("status").asText()).isEqualTo("LIVE");
         }
     }