refactor: update AppState references to use state module

- Change all instances of AppState to reference the new state module across multiple files for consistency.
- Clean up imports in auth, books, index_jobs, libraries, pages, search, settings, thumbnails, and tokens modules.
- Simplify main.rs by removing unused code and organizing middleware and route handlers under the new handlers module.

apps/indexer/src/lib.rs

@@ -0,0 +1,20 @@
+pub mod api;
+pub mod batch;
+pub mod job;
+pub mod meili;
+pub mod scheduler;
+pub mod scanner;
+pub mod utils;
+pub mod watcher;
+pub mod worker;
+
+use sqlx::PgPool;
+
+#[derive(Clone)]
+pub struct AppState {
+    pub pool: PgPool,
+    pub meili_url: String,
+    pub meili_master_key: String,
+    pub api_base_url: String,
+    pub api_bootstrap_token: String,
+}