History mode: no chronological list of executed activities (activity instance history with timestamps)

[javahippie]

Summary

The process instance history view has no chronological record of all executed elements — there is no table showing which activities (start events, service tasks, user tasks, gateways, end events, …) ran, in which order, with which timestamps.

Current state

• No component fetches GET /history/activity-instance anywhere in the codebase.
• The closest existing tab, "User Tasks", queries the runtime task list only (GET /task?processInstanceId={id} via get_process_instance_tasks) — completed tasks never appear, and for finished instances the tab is permanently empty. Historic sources (/history/task, /history/activity-instance) are unused.

Expected (C7 Cockpit parity)

In history mode, a chronological activity table for the instance: activity name, activity type, start time, end time, duration, canceled marker — sourced from

GET /history/activity-instance?processInstanceId={id}&sortBy=startTime&sortOrder=asc

This is the same data source needed for the historic diagram badges (#99) — one new history resource function + signal serves both.

Suggested implementation

• history.activity_instance.by_process_instance resource function + signal in state.js.
• New history-mode tab (same conditional-tab mechanism as the Audit Log tab, Process instance history view: add "Audit Log" tab (user operation log, C7 Cockpit parity) #93), table columns as above; timestamps via <time> like the existing tables; activity names come directly from the REST payload (activityName), no BPMN mapping needed.
• Optionally enrich the User Tasks tab with historic task details (assignee, due date via /history/task) as a separate step — the activity table above already covers the "what ran when" question for all element types.