[codex] restore Security and Data docs

[Abhishek Patil (abhishekpatil4)]

Summary

Restores the Security and Data docs section that was added in #3525 and later temporarily reverted in #3668.

The original content applies cleanly with one current-docs adjustment: the docs navigation has changed since June, so the restored section now sits below the current Triggers pages and before the legacy Direct Tool Execution section. I also updated stale internal links to the current Proxy Execute and Custom OAuth webhook docs paths.

Validation

• pnpm --dir docs lint:links
• pnpm --dir docs types:check
• pnpm --dir docs build

Note: the build emits existing warnings about COMPOSIO_API_KEY not being set for toolkit detail fetches and repeated Fumadocs OpenAPI notices for openapi-v3.json; it completes successfully.

[vercel]

Abhishek Patil (@abhishekpatil4) is attempting to deploy a commit to the Composio Team on Vercel.

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