Add Arabic pronunciation processing

docs/ARCHITECTURE.md

@@ -58,6 +58,16 @@ retry delay when available, and propagates cancellation without retrying.
 A deterministic layer converts the approved SongProject into the final
 Suno-facing lyrics/style content. User choices override AI suggestions.
 
+## Arabic Pronunciation Processor
+
+The Arabic Pronunciation Processor is a local Application Service. It
+normalizes user-supplied Arabic diacritics and applies the selected
+tanween policy without choosing a diacritization policy for the user.
+It must not invent missing vowel marks or tanween when no reliable
+linguistic source is available; instead, it returns a review note so a
+later user-review flow can present the unresolved text. This processor
+does not use external services or APIs.
+
 ## Security
 
 -   Never commit API keys to source control.

docs/TASKS.md

@@ -68,7 +68,7 @@ requirement is missing and blocks implementation, record it in
 ## Phase 5 --- Arabic Lyrics Processing
 
 -   [x] Add Arabic-specific settings UI.
--   [ ] Support diacritics/harakat/tanween processing.
+-   [x] Support diacritics/harakat/tanween processing.
 -   [ ] Preserve intentional spelling/dialect choices where possible.
 -   [ ] Allow user to compare/edit processed Arabic before Suno handoff.
 -   [ ] Add Arabic test fixtures covering multiple dialects.