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-infra/src/database.rs

@@ -1,9 +1,3 @@
-#![allow(
-    clippy::cast_possible_truncation,
-    clippy::cast_sign_loss,
-    clippy::cast_precision_loss,
-    clippy::cast_possible_wrap
-)]
 //! SQLite database connection pool initialisation and schema migrations.
 //!
 //! Uses `r2d2` + `r2d2_sqlite` for connection pooling with the same

crates/zesdex-infra/src/jwt.rs

@@ -1,9 +1,3 @@
-#![allow(
-    clippy::cast_possible_truncation,
-    clippy::cast_sign_loss,
-    clippy::cast_precision_loss,
-    clippy::cast_possible_wrap
-)]
 //! JWT token utilities for HMAC-SHA256 / HS256 signing and verification.
 //!
 //! Uses the `jsonwebtoken` crate under the hood.

crates/zesdex-infra/src/password.rs

@@ -1,9 +1,3 @@
-#![allow(
-    clippy::cast_possible_truncation,
-    clippy::cast_sign_loss,
-    clippy::cast_precision_loss,
-    clippy::cast_possible_wrap
-)]
 //! Argon2 password hashing and verification utilities.
 //!
 //! Uses the `argon2` crate (Argon2id variant) with default parameters,

crates/zesdex-infra/src/state.rs

@@ -1,9 +1,3 @@
-#![allow(
-    clippy::cast_possible_truncation,
-    clippy::cast_sign_loss,
-    clippy::cast_precision_loss,
-    clippy::cast_possible_wrap
-)]
 //! Application state initialisation and wiring.
 //!
 //! This module acts as the composition root for the zesdex daemon (and