fix: resolve warning noise, docs drift, and coverage gaps

[jsugg]

Summary

• close the warning-noise gap by sharing and scoping handcrafted feature warning filters
• repair stale architecture doc references and add a stable ADR index
• add organized unit and integration coverage for DSP, runtime benchmark, runtime environment, and in-process transcription helpers

Notes

• the living implementation plan is tracked in .local/resolve-open-risks.md
• the external validation target /Users/juanpedrosugg/dev/github/strongclaw/.local/resolve-open-risks.md was not present locally, so validation was performed against the in-repo living document instead