perf: findings 6.1, 6.2, 2.6 — async Argon2, moka cache, full streaming migration

- 6.1: PasswordHasherPort now async_trait with spawn_blocking for Argon2
- 6.2: OIDC pending maps migrated from std::sync::Mutex to moka::sync::Cache with TTL
- 2.6: All file download paths migrated to 64KB streaming (get_file_stream / read_blob_stream)
  - WOPI, dedup, batch ZIP, file_retrieval_service consumers migrated
  - WebDAV COPY uses zero-copy dedup (copy_file)
  - Removed dead code: get_file_content, get_file_mmap, read_blob, read_blob_bytes
    from traits, impls, stubs, and mocks (18 files touched)

src/infrastructure/repositories/pg/file_blob_read_repository.rs

@@ -207,11 +207,6 @@ impl FileReadPort for FileBlobReadRepository {
         self.resolve_blob_hash(file_id).await
     }
 
-    async fn get_file_content(&self, id: &str) -> Result<Vec<u8>, DomainError> {
-        let blob_hash = self.resolve_blob_hash(id).await?;
-        self.dedup.read_blob(&blob_hash).await
-    }
-
     async fn get_file_stream(
         &self,
         id: &str,
@@ -239,13 +234,6 @@ impl FileReadPort for FileBlobReadRepository {
         Ok(Box::new(stream))
     }
 
-    async fn get_file_mmap(&self, id: &str) -> Result<Bytes, DomainError> {
-        // For RPi targets, mmap is less beneficial than streaming.
-        // Keep as a fallback that loads content for small/medium files.
-        let blob_hash = self.resolve_blob_hash(id).await?;
-        self.dedup.read_blob_bytes(&blob_hash).await
-    }
-
     async fn get_file_path(&self, id: &str) -> Result<StoragePath, DomainError> {
         let row = sqlx::query_as::<_, (String, Option<String>)>(
             r#"