Handle edge cases in caching

**Feature request**
It would be great to have caching for routes.

**Use case**
Many users need this functionality for production deployments.

**Implementation idea**
Add a new config option `enable_caching` with default `false`.

The issue names no files or tests. Start by locating route handling and configuration loading in the Shell project, then clarify what is cached, its lifetime, and how invalidation works. Done should include a defined route-caching behavior and a configuration option that remains disabled by default, backed by tests.

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