refactor(providers): update google SDK to google-genai and model to gemini-2.5-flash-lite

[thaikolja]

Okay, here we have a much cleaner PR focusing only on Google

Description

This PR addresses the outdated Google SDK issue by migrating the Google provider from the deprecated google-generativeai library to the official, supported google-genai SDK. It also updates the default model from the deprecated gemini-2.0 family to gemini-2.5-flash-lite.

Changes Made

• Dependencies: Replaced google-generativeai~=0.8 with google-genai>=0.3.0 in pyproject.toml. Added SDK updates to uv.lock.
• Provider Implementation: Refactored src/shelloracle/providers/google.py to use genai.Client and the asynchronous client.aio.models.generate_content_stream method. Updated default model to gemini-2.5-flash-lite.
• Stream Handling: Updated the async generator to properly validate and yield chunk.text.

Testing

• Dependency resolution and lockfile synchronization (uv sync)
• Passed existing automated testing suite (uv run pytest)
• Passed type boundaries (uv run hatch run types:check)

uv hatch run types:check Output:

Success: no issues found in 20 source files
Success: no issues found in 9 source files

uv run pytest Output:

============================= test session starts ==============================
platform darwin -- Python 3.13.12, pytest-8.4.2, pluggy-1.6.0
rootdir: /Users/kolja/Coding/Python/ShellOracle
configfile: pyproject.toml
plugins: anyio-4.12.1, cov-5.0.0, xdist-3.8.0, httpx-0.35.0, sugar-1.1.1, asyncio-0.26.0
asyncio: mode=Mode.STRICT, asyncio_default_fixture_loop_scope=function, asyncio_default_test_loop_scope=function
collected 36 items

tests/providers/test_deepseek.py ....                                    [ 11%]
tests/providers/test_localai.py ...                                      [ 19%]
tests/providers/test_ollama.py ......                                    [ 36%]
tests/providers/test_openai.py ....                                      [ 47%]
tests/providers/test_xai.py ....                                         [ 58%]
tests/test_config.py ........                                            [ 80%]
tests/test_shelloracle.py .......                                        [100%]

============================== 36 passed in 0.74s ==============================

Related Issues

• Fixes Bug: google.generativeai is no longer operational #89

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[djcopley]

lgtm