fix(lint): resolve 35 clippy warnings across Rust codebase

Fix all clippy warnings reported by `cargo clippy --lib`:

- codex_config.rs: fix doc_overindented_list_items (3 spaces -> 2)
- commands/copilot.rs: inline format args in 2 log::error! calls
- commands/provider.rs: inline format args in 3 map_err closures
- proxy/hyper_client.rs: inline format arg in log::debug! call
- proxy/providers/copilot_auth.rs: inline format args in 16 locations
  (log macros, format! in headers, error constructors)
- proxy/thinking_optimizer.rs: inline format args in 2 log::info! calls
- services/skill.rs: inline format args in log::debug! call
- services/webdav_sync.rs: inline format args in 6 format! calls
  (version compat messages, download limit messages)
- services/webdav_sync/archive.rs: inline format args in 2 format! calls
- session_manager/providers/opencode.rs: inline format args in
  source_path format!

All fixes use the clippy::uninlined_format_args suggestion pattern:
  format!("msg: {}", var)  ->  format!("msg: {var}")

src-tauri/src/codex_config.rs

@@ -141,7 +141,7 @@ pub fn read_and_validate_codex_config_text() -> Result<String, AppError> {
 ///
 /// Supported fields:
 /// - `"base_url"`: writes to `[model_providers.<current>].base_url` if `model_provider` exists,
-///    otherwise falls back to top-level `base_url`.
+///   otherwise falls back to top-level `base_url`.
 /// - `"model"`: writes to top-level `model` field.
 ///
 /// Empty value removes the field.