Update allowed notifications

[roznawsk]

Description

Describe your changes.

Motivation and Context

Why is this change required? What problem does it solve? If it fixes an open
issue, please link to the issue here.

Documentation impact

• Documentation update required
• Documentation updated in another PR
• No documentation update required

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to
  not work as expected)

[linear]

FCE-3215 Fix allowed notifications in python sdk

[Copilot]

Pull request overview

This PR updates which server notifications are surfaced by the SDK, aligning ALLOWED_NOTIFICATIONS with newer proto message types and adding tests to ensure future proto changes require an explicit maintainer decision.

Changes:

• Add ServerMessageChannelAdded/Removed and switch from deprecated ServerMessageStreamConnected/Disconnected to ServerMessageStreamerConnected/Disconnected in ALLOWED_NOTIFICATIONS.
• Re-export the newly-allowed notification types from fishjam.events.
• Add a regression test that asserts every ServerMessage.content oneof member is either allowed or explicitly ignored, and that allowed notifications are re-exported.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

File	Description
tests/test_allowed_notifications.py	Adds tests to enforce an explicit allow/ignore decision for new ServerMessage.content oneof members and verifies re-exports.
fishjam/events/allowed_notifications.py	Updates the allowed notification set/type union to include channel events and streamer connect/disconnect events.
fishjam/events/__init__.py	Re-exports the newly allowed proto message types via imports and __all__.
AGENTS.md	Adds a short development workflow guideline document (TDD red/green/refactor).

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.