Security: Fix SQL injection vulnerabilities in PostgreSQL storage

[lucky-verma]

• Replace string interpolation with parameterized queries using ANY($n)
• Update get_by_ids to use secure parameter binding
• Fix filter_keys methods in KVStorage and VectorDBStorage
• Add explicit whitelist validation in get_docs_paginated
• Resolves 5 high-severity SQL injection vulnerabilities

[danielaskdd]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Keep them coming!

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[danielaskdd]

Thanks for sharing.