fix: Add missing service calendar in TestStopHandlerMultiAgencyScenario

[ARCoder181105]

Description

Fixes a FOREIGN KEY constraint failed error in TestStopHandlerMultiAgencyScenario by adding the missing calendar/service entry that trips reference.

Problem

The test creates trips with ServiceID: "service1" but never creates the corresponding calendar entry in the database, causing the test to fail with:

FOREIGN KEY constraint failed
Error Trace: /internal/restapi/stop_handler_test.go:214

Solution

Added CreateCalendar call to create the service1 calendar entry before creating trips that reference it.

Changes

• Added calendar creation in TestStopHandlerMultiAgencyScenario (line ~205)
• Ensures foreign key constraint trips.service_id → calendar.id is satisfied

Testing

go test -v ./internal/restapi -run TestStopHandlerMultiAgencyScenario

✅ Test now passes

Related

• Discovered while investigating CI failures in PR fix: Correct route agency ID generation in arrival-and-departure-for-stop handler #350
• This is a pre-existing test infrastructure bug, unrelated to any feature changes

[aaronbrethorst]

nice work, thanks for tracking this down and fixing it.