feat: Add RO chat event schema

[Matovidlo]

Before asking for review make sure that:

• you created a task for KBC team to update event-schema in Connection (validation in API endpoint)
  • https://linear.app/keboola/issue/DMD-761/update-event-schema
• you notified everyone in #general that even schema is changing

[Copilot]

Pull Request Overview

Adds a new JSON schema for the ext.keboola.ro-chat event and corresponding test fixtures covering several serverTransport variants.

• Introduces schema/ext.keboola.ro-chat.json defining mcpServerContext, message, and tool structure (with transport enum).
• Adds four event fixture JSON files exercising presence/absence and different values of serverTransport (http, sse, omitted).

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
schema/ext.keboola.ro-chat.json	New schema defining structure and enum for serverTransport and tool arguments.
tests/events/ext.keboola.ro-chat.json	Base event fixture with serverTransport http.
tests/events/ext.keboola.ro-chat.http.json	Event fixture explicitly for http transport.
tests/events/ext.keboola.ro-chat.sse.json	Event fixture for sse transport.
tests/events/ext.keboola.ro-chat.no-transport.json	Event fixture omitting serverTransport to validate optionality.

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[vita-stejskal]

LGTM

[AdamVyborny]

LGTM