feat: release configurable API response contracts

Define reusable response bodies in .api with typed code mappings, per-route overrides and matching OpenAPI schemas. Add application and callback encoders, early response policy selection, and isolated remote-consumer release verification.

Release v0.8.0-preview after full race, vet, build and local MySQL workflow acceptance.

examples/userService/internal/handler/responseGen.go

@@ -0,0 +1,30 @@
+// Code generated by go-omni api. DO NOT EDIT.
+package handler
+
+import (
+	"encoding/json"
+	"git.yuntuo.hk/k2safe/go-omni/response"
+	"strings"
+)
+
+var responseTemplates = map[string]response.Encoder{"": response.Default()}
+
+func newResponseTemplate(raw string) response.Encoder {
+	var cfg response.Config
+	decoder := json.NewDecoder(strings.NewReader(raw))
+	decoder.UseNumber()
+	if err := decoder.Decode(&cfg); err != nil {
+		panic(err)
+	}
+	return response.MustNew(cfg)
+}
+func responseEncoder(name string, raw bool) response.Encoder {
+	encoder := responseTemplates[name]
+	if encoder == nil {
+		panic("unknown response template")
+	}
+	if raw {
+		encoder = response.RawJSON(encoder)
+	}
+	return encoder
+}