gokv v1
endpoints:
  GET    /kv/:ns/:key   read value
  PUT    /kv/:ns/:key   write value (max 1 MB)
  DELETE /kv/:ns/:key   delete value
  HEAD   /kv/:ns/:key   check existence
  GET    /kv/:ns        list keys (max 10000 returned)
  GET    /health        liveness probe
  GET    /admin/stats   stats (auth required)
  POST   /admin/compact compact db (auth required)

auth: Authorization: Bearer <token>
namespace/key: ^[a-zA-Z0-9._-]{1,128}$