fix: Resolve Clippy CI failures from elided lifetime warnings

The latest Rust nightly compiler (2025-08-27) introduced the
elided-named-lifetimes lint which causes Clippy CI checks to fail
when an elided lifetime ('_) resolves to a named lifetime that's
already in scope.

This commit fixes the Clippy warnings by:
- Making lifetime relationships explicit where 'a is already in scope
- Keeping elided lifetimes ('_) in functions without explicit
  lifetime parameters
- Ensuring proper lifetime handling in the database pool module

Affected files (17 total):
- Database map modules: Handle, Key, and KeyVal references in get,
  qry, keys, and stream operations
- Database pool module: into_recv_seek function

This change resolves the CI build failures without changing any
functionality, ensuring the codebase remains compatible with the
latest nightly Clippy checks.

src/service/presence/mod.rs

@@ -183,8 +183,8 @@ impl Service {
 			.services
 			.users
 			.list_local_users()
-			.map(UserId::to_owned)
-			.collect::<Vec<_>>()
+			.map(ToOwned::to_owned)
+			.collect::<Vec<OwnedUserId>>()
 			.await
 		{
 			let presence = self.db.get_presence(user_id).await;