Expose searchable Activity history with exact destinations (DRU-511)

[czpython]

Serve Activity history with literal work-label search, exact app and type filters, and inclusive/exclusive UTC date limits. Return stable type choices on the first HTTP page. Use the same eligible records for history and live updates.

Keep recorded labels, run and gate identities, request rounds, reasons, and exact artifact IDs. Report unavailable destinations without removing history. Preserve historical targets through Factory and Python-declared pages. Resume the event stream from its last sequence and read every catch-up page.

Decisions

• Retain existing shared operator authorization and exclude built-in or uninstalled app owners through the installed roster.
• Expose separate subject, run, and artifact availability fields so the client can retain recorded identities.
• Use SSE event IDs and an optional after cursor for reconnect and initial catch-up.