feat: search reindex, worker improvements, person IDs, user display names

- add admin POST /api/v1/admin/reindex-search endpoint + event-driven handler
- backfill persons from movie_cast/movie_crew into persons table
- paginate person list_page/backfill_from_credits_batch to cap memory
- concurrent worker event dispatch with semaphore (max 8)
- graceful worker shutdown (drain in-flight tasks on SIGINT)
- always ack events, log handler errors as warnings (no infinite retry)
- NATS ack_wait 600s, AtomicBool guard against concurrent reindex
- add username/display_name to UserSummaryDto and users list
- add person_id to CastMemberDto/CrewMemberDto via get_movie_profile use case
- add movie_id to wrapup MovieRef, person_id to wrapup PersonStat
- thread tmdb_person_id through wrapup cast pipeline
- add is_federated to FeedEntryDto
- cap orphaned persons query with LIMIT 500
- add SPA link to classic site footer

crates/api-types/src/diary.rs

@@ -57,6 +57,7 @@ pub struct FeedEntryDto {
     pub user_id: Uuid,
     pub user_email: String,
     pub user_display_name: String,
+    pub is_federated: bool,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize, utoipa::ToSchema)]

crates/api-types/src/movies.rs

@@ -40,6 +40,7 @@ pub struct KeywordDto {
 
 #[derive(Debug, Clone, Serialize, Deserialize, utoipa::ToSchema)]
 pub struct CastMemberDto {
+    pub person_id: String,
     pub tmdb_person_id: u64,
     pub name: String,
     pub character: String,
@@ -49,6 +50,7 @@ pub struct CastMemberDto {
 
 #[derive(Debug, Clone, Serialize, Deserialize, utoipa::ToSchema)]
 pub struct CrewMemberDto {
+    pub person_id: String,
     pub tmdb_person_id: u64,
     pub name: String,
     pub job: String,

crates/api-types/src/users.rs

@@ -7,6 +7,8 @@ use crate::diary::{DiaryEntryDto, DiaryResponse};
 pub struct UserSummaryDto {
     pub id: Uuid,
     pub email: String,
+    pub username: String,
+    pub display_name: Option<String>,
     pub total_movies: i64,
     pub avg_rating: Option<f64>,
 }