refactor: group use cases into DDD bounded contexts

Flat use_cases/ (44 files) + monolithic commands.rs/queries.rs
split into diary/, movies/, watchlist/, import/, auth/, users/,
integrations/, search/, person/, federation/ — each with own
commands.rs, queries.rs, and use case modules.

Inline tests extracted to sibling tests/ dirs.

crates/application/src/diary/log_review.rs

@@ -0,0 +1,98 @@
+use domain::{
+    errors::DomainError,
+    events::DomainEvent,
+    models::{Movie, Review},
+    value_objects::{Comment, MovieId, Rating, UserId},
+};
+
+use crate::{
+    context::AppContext,
+    diary::commands::LogReviewCommand,
+    diary::movie_resolver::{MovieResolver, MovieResolverDeps},
+};
+
+pub async fn execute(ctx: &AppContext, cmd: LogReviewCommand) -> Result<(), DomainError> {
+    let rating = Rating::new(cmd.rating)?;
+    let user_id = UserId::from_uuid(cmd.user_id);
+    let comment = cmd.comment.clone().map(Comment::new).transpose()?;
+
+    let (movie, is_new_movie) = if let Some(id) = cmd.input.movie_id {
+        let movie_id = MovieId::from_uuid(id);
+        let movie = ctx
+            .repos
+            .movie
+            .get_movie_by_id(&movie_id)
+            .await?
+            .ok_or_else(|| DomainError::NotFound(format!("Movie {id}")))?;
+        (movie, false)
+    } else {
+        let deps = MovieResolverDeps {
+            repository: ctx.repos.movie.as_ref(),
+            metadata_client: ctx.services.metadata.as_ref(),
+        };
+        MovieResolver::default_pipeline()
+            .resolve(&cmd.input, &deps)
+            .await?
+    };
+
+    ctx.repos.movie.upsert_movie(&movie).await?;
+
+    let review = Review::new(movie.id().clone(), user_id, rating, comment, cmd.watched_at)?;
+    let review_event = ctx.repos.review.save_review(&review).await?;
+
+    let was_on_watchlist = ctx
+        .repos
+        .watchlist
+        .remove_if_present(review.user_id(), review.movie_id())
+        .await?;
+    if was_on_watchlist {
+        let _ = ctx
+            .services
+            .event_publisher
+            .publish(&DomainEvent::WatchlistEntryRemoved {
+                user_id: review.user_id().clone(),
+                movie_id: review.movie_id().clone(),
+            })
+            .await;
+    }
+
+    publish_events(ctx, &movie, is_new_movie, review_event).await?;
+
+    Ok(())
+}
+
+#[cfg(test)]
+#[path = "tests/log_review.rs"]
+mod tests;
+
+async fn publish_events(
+    ctx: &AppContext,
+    movie: &Movie,
+    is_new_movie: bool,
+    review_event: DomainEvent,
+) -> Result<(), DomainError> {
+    if is_new_movie && let Some(ext_id) = movie.external_metadata_id() {
+        let discovery_event = DomainEvent::MovieDiscovered {
+            movie_id: movie.id().clone(),
+            external_metadata_id: ext_id.clone(),
+        };
+        ctx.services
+            .event_publisher
+            .publish(&discovery_event)
+            .await?;
+    }
+
+    if let Some(ext_id) = movie.external_metadata_id() {
+        let enrichment_event = DomainEvent::MovieEnrichmentRequested {
+            movie_id: movie.id().clone(),
+            external_metadata_id: ext_id.value().to_string(),
+        };
+        ctx.services
+            .event_publisher
+            .publish(&enrichment_event)
+            .await?;
+    }
+
+    ctx.services.event_publisher.publish(&review_event).await?;
+    Ok(())
+}