Add summary column to workflows table

What does this MR do and why?

Adds summary column to workflows table, from #594334 (comment 3258820250)

Summary column will be used to describe the workflow, or error state if it fails.

Up

❯ bin/rails db:migrate:up:main VERSION=20260415194113
main: == [advisory_lock_connection] object_id: 140340, pg_backend_pid: 31492
main: == 20260415194113 AddSummaryToDuoWorkflowsWorkflows: migrating ================
main: -- add_column(:duo_workflows_workflows, :summary, :text, {:null=>true, :if_not_exist=>true})
main:    -> 0.0067s
main: -- transaction_open?(nil)
main:    -> 0.0000s
main: -- transaction_open?(nil)
main:    -> 0.0000s
main: -- execute("ALTER TABLE duo_workflows_workflows\nADD CONSTRAINT check_13bb5688db\nCHECK ( char_length(summary) <= 1024 )\nNOT VALID;\n")
main:    -> 0.0045s
main: -- execute("SET statement_timeout TO 0")
main:    -> 0.0003s
main: -- execute("ALTER TABLE duo_workflows_workflows VALIDATE CONSTRAINT check_13bb5688db;")
main:    -> 0.0014s
main: -- execute("RESET statement_timeout")
main:    -> 0.0003s
main: == 20260415194113 AddSummaryToDuoWorkflowsWorkflows: migrated (0.0752s) =======

main: == [advisory_lock_connection] object_id: 140340, pg_backend_pid: 31492

Down

❯ bin/rails db:migrate:down:main VERSION=20260415194113
main: == [advisory_lock_connection] object_id: 139820, pg_backend_pid: 43053
main: == 20260415194113 AddSummaryToDuoWorkflowsWorkflows: reverting ================
main: -- remove_column(:duo_workflows_workflows, :summary, {:if_exists=>true})
main:    -> 0.0389s
main: == 20260415194113 AddSummaryToDuoWorkflowsWorkflows: reverted (0.0520s) =======

main: == [advisory_lock_connection] object_id: 139820, pg_backend_pid: 43053

References

#594334

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