fix: add litellm[proxy] dependency to fix missing fastapi on fresh install

[RemyLoveLogicAI]

Issue

Fixes #1728

After installing A0 2.0/2.1 from a fresh environment, users encounter:

litellm.exceptions.APIConnectionError: APIConnectionError: DeepseekException - Missing dependency No module named 'fastapi'. Run `pip install 'litellm[proxy]'`

Root Cause

The litellm package lists fastapi as an optional dependency under the [proxy] extra. Without fastapi installed, litellm cannot make HTTP connections and raises APIConnectionError.

Fix

Change the litellm dependency in requirements.txt from:

-litellm==1.88.1  # CVE-2026-42271 fix: patched floor is 1.83.7
+litellm[proxy]==1.88.1  # CVE-2026-42271 fix: patched floor is 1.83.7

Adding the [proxy] extra ensures fastapi (and other proxy-related dependencies) are installed automatically alongside litellm.

Verification

• Only requirements.txt is modified
• The version pin (==1.88.1) and CVE comment are preserved
• No other dependencies or files are affected

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Avoid installing proprietary LiteLLM enterprise code

In fresh installs (including Docker builds that run uv pip install -r /git/agent-zero/requirements.txt), the proxy extra does much more than add FastAPI: LiteLLM 1.88.1 declares litellm-enterprise==0.1.42; extra == "proxy", and that package is published as LicenseRef-Proprietary. This pulls proprietary enterprise code into every MIT Agent Zero installation even though the repo only imports the LiteLLM SDK; adding the missing FastAPI/Starlette dependencies directly would avoid changing the redistribution/licensing footprint.

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