sysview: fix cycle-3 review findings

- kill_traffic(): stop the recording at --duration-ms exactly, then reap
  the workload, instead of waiting on it (up to 60s) before -stop
- sysview_report.py: key open_calls by (func id, context) so interleaved
  callers of the same function don't cross-pair CALL/RET
- build.yml: intersect the sysview dep-fetch board list with the PR's own
  HIL selection (tinyusb.json vs hfp.json), and skip entirely when HIL is
  not running for this PR
- nrf54h20dk: shrink SYSVIEW_BUFFER_SIZE_DEFAULT to 4096 -- .data/.bss sit
  in the 32 KiB primary RAM, so the family's 65536 default fails to link
- tusb_sysview.c: copy pcTaskName into a local buffer at snapshot time so
  a task deleted mid-lap can't leave SendTaskInfo() dereferencing a freed TCB
- sysview_ci.py: drop a comparison against a baseline whose capture config
  (example/workload/duration_s) changed, and fail cdc_burst when the link
  stays enumerated but echoes nothing back
- SKILL.md: document the WCH post-mortem dump path (OpenOCD, no J-Link)