Add versioned URL updates with history/restore + clippy reverse sort fixes

[Copilot]

Add support for updating a short link’s destination while retaining a full, queryable history, without impacting hot-path reads. Ensure transactional integrity, cache invalidation, and resolve clippy’s reverse-sort warnings.

• Data models & storage API

  • Added URL history entry + update/restore request models and storage trait methods.

• Storage implementations (Postgres/SQLite)

  • Created url_history table + index.
  • Implemented transactional update/restore flows and history retrieval.
  • Cached storage now invalidates on update/restore.

• API surface

  • Added update, history, and restore handlers/routes with owner/admin authorization.

• Clippy cleanup

  • Replaced reverse sort_by with sort_by_key(Reverse(...)).

Example (reverse sort idiom used):

result.sort_by_key(|item| std::cmp::Reverse(item.visit_count));