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/files.rs

@@ -16,7 +16,6 @@ use crate::file_types;
 use crate::geo::{gps_bounding_box, haversine_distance};
 use crate::memories::extract_date_from_filename;
 use crate::{AppState, create_thumbnails};
-use actix_web::dev::ResourcePath;
 use actix_web::web::Data;
 use actix_web::{
     HttpRequest, HttpResponse,
@@ -1242,6 +1241,7 @@ mod tests {
     }
 
     impl FakeFileSystem {
+        #[allow(dead_code)]
         fn with_error() -> FakeFileSystem {
             FakeFileSystem {
                 files: HashMap::new(),