fix: encode interaction media bytes

[pragnyanramtha]

Fixes #2427.

Summary

• treat raw bytes as valid Interactions base64 media input
• base64-encode raw bytes in both sync and async request transforms
• add regression coverage for image, audio, video, and document content blocks so transformed requests remain JSON-serializable

Tests

• .venv/bin/pytest google/genai/tests/interactions/test_base64_inputs.py google/genai/tests/interactions/test_auth.py google/genai/tests/interactions/test_integration.py -q
• .venv/bin/python -m compileall -q google/genai/_interactions/_files.py google/genai/_interactions/_types.py google/genai/_interactions/_utils/_transform.py google/genai/tests/interactions/test_base64_inputs.py
• git diff --check

Note: I also ran pytest google/genai/tests/interactions -q; the non-credential tests passed, but test_paths.py requires local API key/ADC credentials and failed during fixture setup before exercising this patch.

[pragnyanramtha]

Refreshed this branch with current main and re-ran the focused validation.

Validation:

• .venv/bin/pytest google/genai/tests/interactions/test_base64_inputs.py google/genai/tests/interactions/test_auth.py google/genai/tests/interactions/test_integration.py -q -> 29 passed
• .venv/bin/python -m compileall -q google/genai/_interactions/_files.py google/genai/_interactions/_types.py google/genai/_interactions/_utils/_transform.py google/genai/tests/interactions/test_base64_inputs.py -> passed
• git diff --check origin/main...HEAD -> passed

[pragnyanramtha]

Refreshed this branch with current main in 8241320.

Validation rerun after the base update:

• .venv/bin/python -m pytest google/genai/tests/interactions/test_base64_inputs.py google/genai/tests/interactions/test_auth.py google/genai/tests/interactions/test_integration.py -q -> 29 passed, 1 experimental warning
• .venv/bin/python -m compileall -q google/genai/_interactions/_files.py google/genai/_interactions/_types.py google/genai/_interactions/_utils/_transform.py google/genai/tests/interactions/test_base64_inputs.py -> passed
• git diff --check origin/main...HEAD -> passed

[Venkaiahbabuneelam]

Hi @pragnyanramtha, Thanks for reaching out us!

Some checks have failed, please resolve the conflicts.
Thanks

[amirulhafiz1132002-code]

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isinstance(obj , io.IOBase)
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import io
import os