Document file content response handling

[Jaksenc]

Summary

• document that client.files.content() returns a web-standard Response and show reading it with .text()
• align the exported FileContent alias with the actual response type

Closes #958.

Validation

• git diff --check
• npx --yes prettier@3.7.1 --check src/resources/files.ts
• ./node_modules/.bin/tsc --noEmit --pretty false --target es2020 --lib es2020 --module commonjs --moduleResolution node --esModuleInterop --strict --skipLibCheck src/resources/files.ts

Note: full tsc --noEmit still requires optional example dependencies such as @azure/identity, express, and next.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Use a binary-safe read method in file content example

Reading files.content() with response.text() only works for UTF-8 text files; for binary uploads (for example images, PDFs, or arbitrary user_data bytes), this decodes and corrupts the original byte stream. Since this snippet is presented as the general way to retrieve file contents, users following it for non-text files will get damaged data; the example should use a binary-safe method (such as arrayBuffer()) or clearly scope .text() to text-only files.

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