* docs: update GOOGLE_GENAI_USE_VERTEXAI to GOOGLE_GENAI_USE_ENTERPRISE in configs and models
* docs: update GOOGLE_GENAI_USE_VERTEXAI in deployment and setup guides
* docs: update GOOGLE_GENAI_USE_VERTEXAI and Client parameter in integrations and streaming docs
* docs: update GOOGLE_GENAI_USE_VERTEXAI in tutorials and examples
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Co-authored-by: Joe Fernandez <931947+joefernandez@users.noreply.github.com>
* ci: pin actions to SHAs and harden workflows with zizmor auto-fixes
* ci: set least-privilege GITHUB_TOKEN permissions on workflows
* ci: move PR/issue context into env vars to prevent template injection