caching redundency

- after having added Redis (https://github.com/AcevedoR/rpg-maestro/issues/47) I could add something like Aiven Valkey free tiers as a backup plan for Key/value store

No files or tests are named. Start by locating where the Redis/key-value cache is configured and initialized in the TypeScript app, including connection settings and cache read/write paths. Review issue #47 context to match existing Redis decisions, then design where a Valkey backup or fallback switch would fit in that flow. Mark the issue done when config/docs describe how to enable/use the backup store and cache behavior still works after toggling providers.

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