chore: apply cargo fmt + clippy cleanup across crate

Silence forward-looking dead_code on unused DAO modules, annotate
individual placeholder items, rewrite tautological assert!(true/false)
in token tests as panic! arms, and pick up fmt drift.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/libraries.rs

@@ -32,6 +32,7 @@ impl Library {
     /// Resolve a library-relative path into an absolute `PathBuf` under the
     /// library root. Does not validate traversal — use `is_valid_full_path`
     /// for untrusted input.
+    #[allow(dead_code)]
     pub fn resolve(&self, rel_path: &str) -> PathBuf {
         Path::new(&self.root_path).join(rel_path)
     }
@@ -39,6 +40,7 @@ impl Library {
     /// Inverse of `resolve`: given an absolute path under this library's
     /// root, return the root-relative portion. Returns `None` if the path
     /// is not under the library.
+    #[allow(dead_code)]
     pub fn strip_root(&self, abs_path: &Path) -> Option<String> {
         abs_path
             .strip_prefix(&self.root_path)
@@ -99,10 +101,7 @@ pub fn seed_or_patch_from_env(conn: &mut SqliteConnection, base_path: &str) {
 
     // If no rows exist at all (e.g. table created outside the seeded migration),
     // insert a primary library pointing at BASE_PATH.
-    let total: i64 = libraries::table
-        .count()
-        .get_result(conn)
-        .unwrap_or(0);
+    let total: i64 = libraries::table.count().get_result(conn).unwrap_or(0);
     if total == 0 {
         let now = Utc::now().timestamp();
         let result = diesel::insert_into(libraries::table)
@@ -113,7 +112,10 @@ pub fn seed_or_patch_from_env(conn: &mut SqliteConnection, base_path: &str) {
             })
             .execute(conn);
         match result {
-            Ok(_) => info!("Seeded primary library 'main' with BASE_PATH='{}'", base_path),
+            Ok(_) => info!(
+                "Seeded primary library 'main' with BASE_PATH='{}'",
+                base_path
+            ),
             Err(e) => warn!("Failed to seed primary library: {:?}", e),
         }
     }