feat(visual): standardize OFDM RxMER layout and expand per-channel analysis

- redesign GetCapture-RxMER visual with Device Info block and separate channel sections
- add per-channel and combined RxMER charts with multi-channel support
- overlay regression line on RxMER chart and use high-contrast dashed styling
- add supported modulation count chart with QAM to bits/symbol labels and tooltips
- group metric tags into dB and Bit/QAM sections and move carrier count into chart overlay
- update CODING_AGENTS.md visual standards for Device Info layout and regression line color guidance
- regenerate mkdocs visual docs/previews for GetCapture-RxMER - 2026-02-22 21:19:26

Author: mgarcia01752

CODING_AGENTS.md

@@ -59,3 +59,6 @@
 - Warning = yellow
 - OK = green
 - NOK = red
+- Regression / trend / fitted reference lines must use a high-contrast color distinct from waveform traces (prefer dashed).
+- Default regression/reference line color: white.
+- If white reduces readability against the chart/waveform palette, use a dark red contrast line (for example `#c62828`) or another clearly contrasting color and document the choice in the visual remarks.