doc: api: align core C APIs with Doxygen taxonomy, scheduling, memory, pipeline, and module documentation

[lgirdwood]

Summary

This PR aligns sof-docs with the modernized Doxygen C API taxonomy introduced in SOF firmware PR thesofproject/sof#11296. It expands Sphinx and Breathe integration across core Sound Open Firmware architectural subsystems.

Note

Dependency Notice:
This PR depends on thesofproject/sof#11296 being merged into thesofproject/sof:main first.
The sof-docs CI workflow (.github/workflows/pull-request.yml) clones thesofproject/sof:main directly to generate Doxygen XML. Until PR #11296 merges into sof:main, CI will fail under Sphinx -W because the new Doxygen groups (scheduler_api, memory_api, pipeline_graph_api, module_api, etc.) are not yet present on main.
Verified locally with zero warnings: make html -W SOF_ROOT=../sof-dox-work.

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Key Additions & Changes

1. Breathe Anonymous Struct Warning Suppression (conf.py):

   • In Sphinx C domain, Breathe generates duplicate variable declarations when a C union contains multiple anonymous structs sharing member names (such as scheduler_dp_thread_ipc_param in dp_schedule.h). Added duplicate_declaration.c warning suppression filter to avoid spurious fatal errors under Sphinx -W mode.

2. Memory Management Infrastructure (api/memory.rst):

   • Added dedicated documentation page covering virtual memory regions (vregion), virtual page allocation (vpage), runtime buffer allocator (rballoc), memory tags, capabilities, and physical memory topologies (L2 HP-SRAM, L2 LP-SRAM, L3).
   • Rendered Doxygen groups memory_api and sof_memory_management via Breathe.

3. Scheduling Infrastructure (api/scheduling.rst):

   • Added dedicated documentation page covering Low-Latency (LL) timer and DMA scheduling domains, Dynamic Processing (DP) threads and Zephyr RTOS mapping, legacy EDF and TWB schedulers, task operations, and lifecycle state machines.
   • Rendered Doxygen groups scheduler_api, schedule_task_api, ll_scheduler_api, dp_scheduler_api, edf_scheduler_api, twb_scheduler_api, and zephyr_dp_schedule.

4. Pipeline Modularization:

   • Deconstructed monolithic api/pipeline.rst into focused architectural sub-pages:
     • api/pipeline_graph.rst: Directed Acyclic Graph (DAG) construction, scheduling task binding (LL/DP), traversal, and state transitions.
     • api/component_infra.rst: Unified component driver model (comp_ops), trigger state machines, and multi-core IDC bindings.
     • api/audio_buffer.rst: Interconnect buffers (comp_buffer), circular stream endpoints, and lockless ring buffers.
     • api/audio_format.rst: Channel mapping, PCM sample conversion, and saturation arithmetic.
   • Transformed api/pipeline.rst into an architectural hub page with an overview ASCII diagram and sub-page toctree.

5. Audio Processing Components & Modules (api/components.rst):

   • Populated the components page with the full Module Adapter layer architecture and built-in processing component catalog (Volume, Mixer, EQ, DRC, SRC, ASRC, Smart Amp, Sound Dose).
   • Documented module lifecycle contracts (init, prepare, process, set/get_configuration, reset, free), streaming endpoints, dynamic LLEXT loading, and UUID registration.
   • Integrated full Breathe C API reference for module_api and removed redundant api/modules.rst.

6. Navigation Updates:

   • Updated api/index.rst and api/rtos.rst navigation trees and cross-references.

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