Fix Pollinations token env resolution

[hackall360]

Summary

• ensure the Pages token endpoint reads Pollinations secrets from both Pages and process environments
• allow the client to resolve tokens from Vite and Node environments by broadening env detection and exposing POLLI_* prefixes
• add regression tests covering the serverless function and client env fallbacks

Testing

• npm test

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https://chatgpt.com/codex/tasks/task_b_68c9ec68b054832f88f13352c518a831