feat(deja): add optional deja dependency and feature ladder across crates
Introduce `deja` as a rev-pinned, optional git dependency
(juspay/deja@075a614, default-features=false) and a `deja` cargo feature
across the seven integrating crates (common_utils, diesel_models,
external_services, hyperswitch_domain_models, redis_interface, router_env,
storage_impl) plus an aggregating `deja` feature on router. Every dep is
`optional = true` and only reachable through the `deja` feature, so default
builds carry zero deja crates in the dependency graph. The v2 clippy/check
recipes exclude the v1-only deja feature.
This is the foundation of the record/replay instrumentation stack: it adds
the dependency surface every later boundary site compiles against, while
staying completely inert when the feature is off.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>