#14871: Claude/audit codebase architecture 8a ql2

<!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> This PR adds three new documentation files (`docs/CODE_AUDIT_REPORT.md`, `docs/MODULAR_COMPONENTS.md`, `docs/architecture-audit.md`) describing the repository’s architecture, modular subsystems, and security model. Main issue: several sections hard-code internal file paths / entrypoints and an API function name that do not match the actual code layout (e.g., CLI entrypoint chain and a referenced `server-chat-registry` file; `probeGatewayHealth` example). These mismatches will send contributors to the wrong files and make the docs unreliable as a navigation/debugging aid. <h3>Confidence Score: 3/5</h3> - This PR is mostly safe to merge, but the new docs contain incorrect internal references that should be fixed first. - Changes are docs-only (no runtime impact), but multiple incorrect file-path/entrypoint/API references reduce documentation accuracy and will confuse readers trying to follow the code. - docs/CODE_AUDIT_REPORT.md, docs/MODULAR_COMPONENTS.md, docs/architecture-audit.md <!-- greptile_other_comments_section --> _{(2/5) Greptile learns from your feedback when you react with thumbs up/down!} **Context used:** - Context from `dashboard` - CLAUDE.md ([source](https://app.greptile.com/review/custom-context?memory=fd949e91-5c3a-4ab5-90a1-cbe184fd6ce8)) - Context from `dashboard` - AGENTS.md ([source](https://app.greptile.com/review/custom-context?memory=0d0c8278-ef8e-4d6c-ab21-f5527e322f13)) <!-- /greptile_comment -->