style: apply cargo fmt to entire codebase

Standardize code formatting across all 173 Rust source files
using rustfmt. No functional changes - purely cosmetic.

This establishes a consistent code style baseline for the
project going forward.

src/application/adapters/mod.rs

@@ -1,8 +1,8 @@
 //! Adapters module for translating between external protocols and internal models
 
-pub mod webdav_adapter;
 pub mod caldav_adapter;
 pub mod carddav_adapter;
+pub mod webdav_adapter;
 
 #[cfg(test)]
 mod caldav_adapter_test;