v1: OAuth fixes and other web-related improvements

[FeodorFitsner]

Close #5276

Summary by Sourcery

Fix OAuth flow with cookie-based state persistence, authorize callbacks, and session error handling; improve Session message buffering and async method invocation with timeouts; refactor Alignment API to constants; apply various web, FastAPI, and Flutter client enhancements.

New Features:

• Persist OAuth state via a secure cookie and automatically apply authorization callbacks after redirect
• Add timeout support and cancellation for async UI method invocations in Session

Bug Fixes:

• Raise explicit error when reconnecting to missing or expired sessions in app manager
• Handle BrokenPipeError and general exceptions safely in FastAPI session handler
• Exclude localhost IP from client hash generation for consistent session IDs

Enhancements:

• Refactor Alignment to use class-level constants instead of class methods
• Buffer outgoing messages in Session until WebSocket connection is established
• Simplify Control.invokeMethod listener logic and update Flutter service registries only when UID changes
• Mark certain Page properties with metadata skip flags to exclude from diff payloads

Build:

• Bump uvicorn dependency to >=0.35.0 and switch to websockets-sansio transport

Documentation:

• Update README and code examples to use new Alignment constants

Tests:

• Adjust tests for new Alignment API and updated control diff expectations

Chores:

• Remove deprecated websockets/uvicorn warning filters

[sourcery-ai]

We've reviewed this pull request using the Sourcery rules engine

[cloudflare-workers-and-pages]

Deploying flet-docs with    Cloudflare Pages

Latest commit:	f7fa5f9
Status:	🚫  Build failed.

View logs