Add wh notification decoding

[roznawsk]

Description

Add function that decodes notifications received by webhook.

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-3416

[Copilot]

Pull request overview

This PR adds a webhook-focused decoder that turns raw protobuf webhook bodies into the same typed/mapped notification payloads that the WebSocket notifier emits, including transparent unwrapping of notificationBatch frames.

Changes:

• Added decodeServerNotifications helper for decoding application/x-protobuf webhook bodies into mapped ServerNotification[].
• Refactored notification decoding to a shared extractNotifications() path used by both the WebSocket notifier and the webhook decoder (including batch unwrapping + filtering non-surfaced variants).
• Added test coverage for webhook decoding/batch behavior and strengthened type-level guarantees around ServerNotification.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
packages/js-server-sdk/tests/webhook.test.ts	Adds runtime tests for webhook decoding, payload mapping, batch unwrapping, and supported input types.
packages/js-server-sdk/tests/notifications.test.ts	Adds a type-level test ensuring ServerNotification['type'] matches ExpectedEvents.
packages/js-server-sdk/src/ws_notifier.ts	Switches WS dispatch to use shared extraction/mapping and emit batch contents in wire order.
packages/js-server-sdk/src/webhook.ts	Introduces decodeServerNotifications for decoding raw webhook bodies into mapped notifications.
packages/js-server-sdk/src/notifications.ts	Adds ServerNotification type and extractNotifications() shared decoding/mapping logic.
packages/js-server-sdk/src/index.ts	Exports decodeServerNotifications and ServerNotification from the package entrypoint.
examples/room-manager/src/index.ts	Updates protobuf content-type parsing example to return decoded notifications (supports batched webhooks).

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[czerwiukk]

assuming the emit issue got resolved - lgtm

[czerwiukk]

question: shouldn't it land in ./notifications/?

[roznawsk]

Given that websocket is in its own file, it's ok for WH to be separate (though the amount of code and abstraction is minimal)

[Copilot]

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.