FEATURE: Stream topic summaries. (#23065)

When we receive the stream parameter, we'll queue a job that periodically publishes partial updates, and after the summarization finishes, a final one with the completed version, plus metadata.

`summary-box` listens to these updates via MessageBus, and updates state accordingly.

spec/system/topic_summarization_spec.rb

@@ -1,32 +0,0 @@
-# frozen_string_literal: true
-
-RSpec.describe "Topic summarization", type: :system, js: true do
-  fab!(:user) { Fabricate(:admin) }
-
-  # has_summary to force topic map to be present.
-  fab!(:topic) { Fabricate(:topic, has_summary: true) }
-  fab!(:post_1) { Fabricate(:post, topic: topic) }
-  fab!(:post_2) { Fabricate(:post, topic: topic) }
-
-  let(:plugin) { Plugin::Instance.new }
-
-  let(:expected_summary) { "This is a summary" }
-  let(:summarization_result) { { summary: expected_summary, chunks: [] } }
-
-  before do
-    sign_in(user)
-    strategy = DummyCustomSummarization.new(summarization_result)
-    plugin.register_summarization_strategy(strategy)
-    SiteSetting.summarization_strategy = strategy.model
-  end
-
-  it "returns a summary using the selected timeframe" do
-    visit("/t/-/#{topic.id}")
-
-    find(".topic-strategy-summarization").click
-
-    summary = find(".summary-box .generated-summary p").text
-
-    expect(summary).to eq(expected_summary)
-  end
-end