desloppify: code health overhaul plus abuse hardening (140 green, strict 87.2)

Honest baseline after removing 45 gaming suppressions. Structural: lib/game plus root hooks extraction, CORS origin echo, DEV_ORIGINS layering. Fixes: error-cause binding, discord 5xx split, null-cache guard, co-located tests, rejecting-fetch coverage, naming and typing cleanup, socket controller, cache bound, cascade helpers, latch resets. Hardening: per-IP rate limit on API routes, deterministic-miss UX, retry cooldown plus cap. Suite 140 green, build plus lint clean.

lib/i18n/get-dictionary.ts

@@ -8,5 +8,5 @@ const dictionaries = { tr, en, de } as const;
 export type Dictionary = typeof tr;
 
 export function getDictionary(locale: Locale): Dictionary {
-    return dictionaries[locale] ?? dictionaries.tr;
+    return dictionaries[locale];
 }