feat(visual): standardize SCQAM spectrum view and fix channel grouping from measurement stats

- redesign GetCapture-SCQAM with standardized header row, optional Capture Time pill, and top Device Info table
- remove fake sysDescr fallbacks and use N/A-safe device info extraction/merge
- group captures by SCQAM channel using measurement_stats channel_stats docsIfDownChannelId (with frequency-range key matching)
- add combined spectrum overlay graph while preserving individual per-channel graphs
- add per-channel Actual / Moving Avg radio toggle (Actual purple, Moving Avg solid red)
- remove redundant per-channel capture parameters panel and channel summary panel
- embed channel summary context into graph titles (Range and Channel Power only)
- remove Meas Status and Meas File columns from the channel details table
- use fixed-height Chart.js 2 containers to avoid Postman resize/stretch issues
- regenerate visual docs/previews for GetCapture-SCQAM - 2026-02-23 01:29:21

Author: mgarcia01752