feat(arr): wire translation backends into daemon

Forward each translate-* feature from arr-daemon to arr-subs, add the
missing OpenAI model bootstrap key, and construct the compiled and
credentialed backends at startup so the translate endpoint stops
answering 503 unconditionally.

crates/arr-daemon/Cargo.toml

@@ -10,6 +10,16 @@ publish = false
 name = "arr"
 path = "src/main.rs"
 
+# Forwards straight to `arr-subs`' own features (DESIGN.md §15): which
+# translators a build ships is a compile-time choice, off by default, same as
+# the crate that implements them.
+[features]
+default = []
+translate-openai = ["arr-subs/translate-openai"]
+translate-deepl = ["arr-subs/translate-deepl"]
+translate-google = ["arr-subs/translate-google"]
+translate-command = ["arr-subs/translate-command"]
+
 [dependencies]
 arr-api = { workspace = true }
 arr-compat = { workspace = true }