chore(hub): clean up legacy Captain hub flow (#13640)

## Summary
This PR cleans up legacy Hub/Captain integration paths and simplifies
hub URL behavior coverage in tests.

## Changes
- remove legacy Captain account endpoint flow from `ChatwootHub`
- remove obsolete spec coverage tied to that retired flow
- keep hub URL handling centralized in `base_url` with enterprise
overlay precedence
- simplify hub URL specs to assert explicit static URL expectations
where applicable

## Reproduce
Run the focused hub specs from this branch:
- `bundle exec rspec spec/lib/chatwoot_hub_spec.rb
spec/enterprise/lib/chatwoot_hub_spec.rb`

## Testing
Validated locally with:
- `bundle exec rspec spec/lib/chatwoot_hub_spec.rb
spec/enterprise/lib/chatwoot_hub_spec.rb`
- `bundle exec rubocop lib/chatwoot_hub.rb spec/lib/chatwoot_hub_spec.rb
enterprise/lib/enterprise/chatwoot_hub.rb
spec/enterprise/lib/chatwoot_hub_spec.rb`

spec/lib/chatwoot_hub_spec.rb

@@ -1,6 +1,13 @@
 require 'rails_helper'
 
 describe ChatwootHub do
+  describe '.base_url' do
+    it 'uses the static hub url' do
+      expect(described_class::DEFAULT_BASE_URL).to eq('https://hub.2.chatwoot.com')
+      expect(described_class.base_url).to eq('https://hub.2.chatwoot.com')
+    end
+  end
+
   it 'generates installation identifier' do
     installation_identifier = described_class.installation_identifier
     expect(installation_identifier).not_to be_nil
@@ -12,7 +19,7 @@ describe ChatwootHub do
       version = '1.1.1'
       allow(RestClient).to receive(:post).and_return({ version: version }.to_json)
       expect(described_class.sync_with_hub['version']).to eq version
-      expect(RestClient).to have_received(:post).with(described_class::PING_URL, described_class.instance_config
+      expect(RestClient).to have_received(:post).with(described_class.ping_url, described_class.instance_config
         .merge(described_class.instance_metrics).to_json, { content_type: :json, accept: :json })
     end
 
@@ -21,7 +28,7 @@ describe ChatwootHub do
       with_modified_env DISABLE_TELEMETRY: 'true' do
         allow(RestClient).to receive(:post).and_return({ version: version }.to_json)
         expect(described_class.sync_with_hub['version']).to eq version
-        expect(RestClient).to have_received(:post).with(described_class::PING_URL,
+        expect(RestClient).to have_received(:post).with(described_class.ping_url,
                                                         described_class.instance_config.to_json, { content_type: :json, accept: :json })
       end
     end
@@ -41,7 +48,7 @@ describe ChatwootHub do
       info = { company_name: company_name, owner_name: owner_name, owner_email: owner_email, subscribed_to_mailers: true }
       allow(RestClient).to receive(:post)
       described_class.register_instance(company_name, owner_name, owner_email)
-      expect(RestClient).to have_received(:post).with(described_class::REGISTRATION_URL,
+      expect(RestClient).to have_received(:post).with(described_class.registration_url,
                                                       info.merge(described_class.instance_config).to_json, { content_type: :json, accept: :json })
     end
   end
@@ -54,7 +61,7 @@ describe ChatwootHub do
       info = { event_name: event_name, event_data: event_data }
       allow(RestClient).to receive(:post)
       described_class.emit_event(event_name, event_data)
-      expect(RestClient).to have_received(:post).with(described_class::EVENTS_URL,
+      expect(RestClient).to have_received(:post).with(described_class.events_url,
                                                       info.merge(described_class.instance_config).to_json, { content_type: :json, accept: :json })
     end
 
@@ -64,29 +71,9 @@ describe ChatwootHub do
         allow(RestClient).to receive(:post)
         described_class.emit_event(event_name, event_data)
         expect(RestClient).not_to have_received(:post)
-          .with(described_class::EVENTS_URL,
+          .with(described_class.events_url,
                 info.merge(described_class.instance_config).to_json, { content_type: :json, accept: :json })
       end
     end
   end
-
-  context 'when fetching captain settings' do
-    it 'returns the captain settings' do
-      account = create(:account)
-      stub_request(:post, ChatwootHub::CAPTAIN_ACCOUNTS_URL).with(
-        body: { installation_identifier: described_class.installation_identifier, chatwoot_account_id: account.id, account_name: account.name }
-      ).to_return(
-        body: { account_email: 'test@test.com', account_id: '123', access_token: '123', assistant_id: '123' }.to_json
-      )
-
-      expect(described_class.get_captain_settings(account).body).to eq(
-        {
-          account_email: 'test@test.com',
-          account_id: '123',
-          access_token: '123',
-          assistant_id: '123'
-        }.to_json
-      )
-    end
-  end
 end