cleanup: strip comments, extract constants, DRY shared helpers across adapters + infra-wiring

- strip all comments except WHY workaround notes (3 remain)
- remove all #[allow(dead_code)]; fix via _prefix rename
- extract named constants: JWT time units, token types, default config values, jellyfin fallback bitrate
- DRY: move serialize_enum_as_string, content_type_str, parse_content_type, parse_genres_blob to adapter-common
- sqlite+postgres library.rs use shared helpers instead of local copies
- sqlite+postgres channel.rs use shared serialize_enum_as_string
- remove dead `let _ = ext` in scanner.rs

crates/adapters/local-files/src/index.rs

@@ -11,7 +11,6 @@ use domain::MediaItemId;
 use crate::config::LocalFilesConfig;
 use crate::scanner::{scan_dir, LocalFileItem};
 
-/// Encode a rel-path string into a URL-safe, padding-free base64 MediaItemId.
 pub fn encode_id(rel_path: &str) -> MediaItemId {
     use base64::Engine as _;
     MediaItemId::new(
@@ -19,7 +18,6 @@ pub fn encode_id(rel_path: &str) -> MediaItemId {
     )
 }
 
-/// Decode a MediaItemId back to a relative path string.
 pub fn decode_id(id: &MediaItemId) -> Option<String> {
     use base64::Engine as _;
     let bytes = base64::engine::general_purpose::URL_SAFE_NO_PAD
@@ -28,11 +26,6 @@ pub fn decode_id(id: &MediaItemId) -> Option<String> {
     String::from_utf8(bytes).ok()
 }
 
-/// In-memory (+ SQLite-backed) index of local video files.
-///
-/// On startup the index is populated from the SQLite cache so the provider can
-/// serve requests immediately. A background task calls `rescan()` to pick up
-/// any changes on disk and write them back to the cache.
 pub struct LocalIndex {
     items: Arc<RwLock<HashMap<MediaItemId, LocalFileItem>>>,
     pub root_dir: PathBuf,
@@ -41,7 +34,6 @@ pub struct LocalIndex {
 }
 
 impl LocalIndex {
-    /// Create the index, immediately loading persisted entries from SQLite.
     pub async fn new(
         config: &LocalFilesConfig,
         pool: sqlx::SqlitePool,
@@ -57,7 +49,6 @@ impl LocalIndex {
         idx
     }
 
-    /// Load previously scanned items from SQLite (instant on startup).
     async fn load_from_db(&self) {
         #[derive(sqlx::FromRow)]
         struct Row {
@@ -107,10 +98,6 @@ impl LocalIndex {
         }
     }
 
-    /// Scan the filesystem for video files and rebuild the index.
-    ///
-    /// Returns the number of items found. Called on startup (background task)
-    /// and via `POST /files/rescan`.
     pub async fn rescan(&self) -> u32 {
         info!(
             "Local files [{}]: scanning {:?}",
@@ -119,7 +106,6 @@ impl LocalIndex {
         let new_items = scan_dir(&self.root_dir).await;
         let count = new_items.len() as u32;
 
-        // Swap in-memory map.
         {
             let mut map = self.items.write().await;
             map.clear();
@@ -129,7 +115,6 @@ impl LocalIndex {
             }
         }
 
-        // Persist to SQLite.
         if let Err(e) = self.save_to_db(&new_items).await {
             error!("Failed to persist local files index: {}", e);
         }
@@ -142,7 +127,6 @@ impl LocalIndex {
     }
 
     async fn save_to_db(&self, items: &[LocalFileItem]) -> Result<(), sqlx::Error> {
-        // Rebuild the table in one transaction, scoped to this provider.
         let mut tx = self.pool.begin().await?;
 
         sqlx::query("DELETE FROM local_files_index WHERE provider_id = ?")
@@ -189,7 +173,6 @@ impl LocalIndex {
             .collect()
     }
 
-    /// Return unique top-level directories as collection names.
     pub async fn collections(&self) -> Vec<String> {
         let map = self.items.read().await;
         let mut seen = std::collections::HashSet::new();