Unify HTTP metadata handling

config/config.exs

@@ -1,8 +1,19 @@
 import Config
 
+project_version =
+  case Mix.Project.config()[:version] do
+    version when is_binary(version) -> version
+    version -> to_string(version)
+  end
+
 config :postgrex, :json_library, JSON
 
 config :parrhesia,
+  metadata: [
+    name: "Parrhesia",
+    version: project_version,
+    hide_version?: true
+  ],
   database: [
     separate_read_pool?: config_env() != :test
   ],

config/runtime.exs

@@ -132,6 +132,7 @@ if config_env() == :prod do
   repo_defaults = Application.get_env(:parrhesia, Parrhesia.Repo, [])
   read_repo_defaults = Application.get_env(:parrhesia, Parrhesia.ReadRepo, [])
   relay_url_default = Application.get_env(:parrhesia, :relay_url)
+  metadata_defaults = Application.get_env(:parrhesia, :metadata, [])
 
   moderation_cache_enabled_default =
     Application.get_env(:parrhesia, :moderation_cache_enabled, true)
@@ -646,6 +647,15 @@ if config_env() == :prod do
 
   config :parrhesia,
     relay_url: string_env.("PARRHESIA_RELAY_URL", relay_url_default),
+    metadata: [
+      name: Keyword.get(metadata_defaults, :name, "Parrhesia"),
+      version: Keyword.get(metadata_defaults, :version, "0.0.0"),
+      hide_version?:
+        bool_env.(
+          "PARRHESIA_METADATA_HIDE_VERSION",
+          Keyword.get(metadata_defaults, :hide_version?, true)
+        )
+    ],
     acl: [
       protected_filters:
         json_env.(