Make FastAPI/JinjaX optional dependencies; add Flask and Litestar adapter stubs

[fsecada01]

Problem

fastapi, uvicorn, and jinjax are currently listed as core (mandatory) dependencies in pyproject.toml:

dependencies = [
    "fastapi>=0.109.0",
    "uvicorn[standard]>=0.27.0",
    "jinjax>=0.41",
    "pydantic>=2.0",   # ← only this belongs here
]

This forces Django users (and any future Flask/Litestar users) to install FastAPI, Uvicorn, and JinjaX even when they will never use them. A Django app using django-cotton for templating must still pull in FastAPI and JinjaX as transitive baggage.

Root-cause analysis

The core package (component_framework/core/) has no imports from fastapi, uvicorn, or jinjax. Those imports exist only inside the adapter files:

File	Imports
adapters/fastapi.py	from fastapi import ...
adapters/fastapi_websocket.py	from fastapi import ...
adapters/jinjax_renderer.py	from jinjax import Catalog

Neither __init__.py is non-empty, so there are no eager re-exports that would force the adapters to load at install time. The fix is purely a pyproject.toml change.

Proposed fix

Move framework-specific packages to optional extras and keep only pydantic as a hard dependency:

dependencies = [
    "pydantic>=2.0",
]

[project.optional-dependencies]
fastapi = [
    "fastapi>=0.109.0",
    "uvicorn[standard]>=0.27.0",
    "jinjax>=0.41",
]
django = [
    "django>=4.2",
    "django-cotton>=0.9",
    "channels>=4.0",
    "channels-redis>=4.1",
]
websockets = [
    "websockets>=12.0",
]
dev = [...]

Install examples:

pip install component-framework[fastapi]        # FastAPI + JinjaX
pip install component-framework[django]         # Django + Channels
pip install component-framework[fastapi,django] # both

Note: This is a minor breaking change for users who relied on implicit FastAPI availability. Should be released in 0.3.0 or with a deprecation path.

Missing adapters

The project currently has no adapters for:

• Flask — widely used WSGI framework; would need a renderer + event dispatcher + optional flask-sock for WebSockets
• Litestar (formerly Starlite) — ASGI, similar surface to FastAPI, growing adoption

These can be tracked as follow-on issues once the optional-extras refactor lands.

CI impact

The test matrix should be updated to verify each extra in isolation (e.g. a [fastapi]-only install doesn't accidentally import django, and vice versa).