feat: configurable trust proxy setting

[giovannibaratta]

This PR adds configuration for the NestJS/Express trust proxy setting to properly handle client IPs when deployed behind Load Balancers, WAFs, and Reverse Proxies. It introduces a new TRUST_PROXY environment variable that supports boolean, numeric (hops), and string (IP ranges/CIDRs) configurations. Empty strings throw an error to prevent silent failures.

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PR created automatically by Jules for task 2489348118601988837 started by @giovannibaratta

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