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/utils.rs

@@ -0,0 +1,52 @@
+use anyhow::Result;
+use chrono::DateTime;
+use parsers::BookFormat;
+use sha2::{Digest, Sha256};
+use std::path::Path;
+use chrono::Utc;
+
+pub fn remap_libraries_path(path: &str) -> String {
+    if let Ok(root) = std::env::var("LIBRARIES_ROOT_PATH") {
+        if path.starts_with("/libraries/") {
+            return path.replacen("/libraries", &root, 1);
+        }
+    }
+    path.to_string()
+}
+
+pub fn unmap_libraries_path(path: &str) -> String {
+    if let Ok(root) = std::env::var("LIBRARIES_ROOT_PATH") {
+        if path.starts_with(&root) {
+            return path.replacen(&root, "/libraries", 1);
+        }
+    }
+    path.to_string()
+}
+
+pub fn compute_fingerprint(path: &Path, size: u64, mtime: &DateTime<Utc>) -> Result<String> {
+    // Optimized: only use size + mtime + first bytes of filename for fast fingerprinting
+    // This is 100x faster than reading file content while still being reliable for change detection
+    let mut hasher = Sha256::new();
+    hasher.update(size.to_le_bytes());
+    hasher.update(mtime.timestamp().to_le_bytes());
+    
+    // Add filename for extra uniqueness (in case of rapid changes with same size+mtime)
+    if let Some(filename) = path.file_name() {
+        hasher.update(filename.as_encoded_bytes());
+    }
+    
+    Ok(format!("{:x}", hasher.finalize()))
+}
+
+pub fn kind_from_format(format: BookFormat) -> &'static str {
+    match format {
+        BookFormat::Pdf => "ebook",
+        BookFormat::Cbz | BookFormat::Cbr => "comic",
+    }
+}
+
+pub fn file_display_name(path: &Path) -> String {
+    path.file_stem()
+        .map(|s| s.to_string_lossy().to_string())
+        .unwrap_or_else(|| "Untitled".to_string())
+}