refactor: consolidate #![allow(clippy::cast_*)] to crate roots

Add the cast-allow block to zesdex-entities/src/lib.rs and
zesdex-utils/src/lib.rs (which lacked it), then remove from
65 sub-files across all 8 crates. Build and all 223 tests
continue to pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/zesdex-cms/src/domain/settings.rs

@@ -5,13 +5,6 @@
 //! This is a pure data structure with **no I/O logic**.  Load/save
 //! responsibilities live in [`SettingsRepository`](super::repository::SettingsRepository).
 
-#![allow(
-    clippy::cast_possible_truncation,
-    clippy::cast_sign_loss,
-    clippy::cast_precision_loss,
-    clippy::cast_possible_wrap
-)]
-
 use std::collections::HashMap;
 
 use serde::{Deserialize, Serialize};