docs: developer_guides: enrich wov-ecns guide context and fix fig223 collision

[lgirdwood]

Description

This PR enriches the WOV-ECNS pipeline customization guide with comprehensive technical context and resolves a visual layout collision in Figure 223:

1. Figure 223 Layout Fix:
   • Expanded SVG canvas to 800px height.
   • Moved Pipeline 107 (ECNS Host Capture) down to y=565, placing it cleanly below Slot 2 (which ends at y=535), eliminating overlapping bounding boxes and lines.
   • Shifted the SOF Notifier Bus to y=705 with routed signal lines.
2. Notifier Registration & Execution Rules:
   • Added registration prototype, callback signatures, and mandatory unregistration lifecycle rules.
   • Detailed real-time callback execution constraints (ISR/high-priority non-blocking context, no dynamic allocations, atomic flag passing).
   • Documented synchronous event dispatch flow and payload definitions.
3. Component Interface Implementation (Step 2):
   • Detailed component lifecycle (init, prepare, process, reset, free).
   • Added multi-pin buffer pointer management, frame iteration math, and runtime IPC parameter handling.
4. IBS / OBS Deep Dive (Step 3):
   • In-depth explanation of input and output buffer sizes in bytes and periods.
   • Clarified how topology parser and scheduler use ibs/obs as scheduling thresholds (data_available >= ibs).
   • Detailed mathematical frame-to-byte formulas for multi-channel pipelines.
5. Context Across Guide:
   • Expanded previously brief sections with detailed context: WOV replacement, cross-core scheduling, NHLT preprocessor usage, ACPI driver override, and hardware test verification runbook.

Signed-off-by: Liam Girdwood liam.r.girdwood@linux.intel.com