feat: harden query read-only workflow

frontend/src/features/ticket/README.md

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+# Ticket Domain
+
+Scope:
+
+- change ticket list
+- ticket create and detail
+- approval timeline
+- execution confirmation and rollback evidence
+- todo / pending work views
+
+Migration targets:
+
+- Split `TicketsPage.tsx` and `TicketDetailPage.tsx` into list, filters, stats, detail header, timeline, SQL diff, approval actions, and execution panels.
+- Keep SQL editor reuse in shared/query components only when it is not ticket-specific.