Add BuildKit cache mounts to Dockerfile

Description

Modify the production Dockerfile to include BuildKit cache mounts for Composer and NPM dependencies to speed up subsequent builds by reusing cached dependency installations

Acceptance Criteria

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• #1 Cache mount for Composer dependencies is added at line 30 with --mount=type=cache target=/var/www/.composer/cache,Cache mount for NPM dependencies is added at line 41 with --mount=type=cache target=/root/.npm,Dockerfile syntax remains valid and builds successfully,All existing functionality is preserved with no regressions

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