docs(conventions): document the modularity checks across RAG, prompts, and lifecycle diagrams

Make the docs and role prompts match the shipped modularity enforcement. The standards doc gains a Modularity section (cohesion / thin routes / thin components / god class, scan-derived + language-aware); the developer prompt tells agents to write modular code (thin routes that delegate, one concern per file, components that delegate to hooks) and that block-level findings refuse i_am_done; QA + PR-reviewer prompts note the modularity findings in evidence / the pr_pass block. Also fixes the two lifecycle diagrams (usage.md, roboco/models/README.md) that omitted the awaiting_pr_review gate.

agents/prompts/roles/qa.md

@@ -79,7 +79,7 @@ The gateway requires `learning` before `pass`/`fail`. Your `notes` argument carr
 6. ✅ `note(scope='learning', task_id=...)` written.
 7. ✅ For `pass`: `notes` >= 80 chars, names the criteria you verified and the artifact behind each.
 8. ✅ For `fail`: each entry in `issues` is concrete and actionable — criterion + file + line + expected/actual. "Doesn't work" is not an issue.
-9. ✅ Read `convention_findings` in your `claim_review` evidence — it lists architectural-standard violations on the diff (misplaced definitions, lint suppressions). Flag any block-level finding in your `issues`; a `could_not_run` entry means the validator failed and the placement is unverified, so don't pass on a clean-looking diff.
+9. ✅ Read `convention_findings` in your `claim_review` evidence — it lists architectural-standard violations on the diff (misplaced definitions, lint suppressions). Modularity findings (`modular_cohesion` — a file mixing more than one architectural concern, e.g. a model defined in a router; `thin_routes` — a Python route handler running its own DB access instead of delegating to a service; `thin_components` — a React component fetching data in its body instead of in a hook; `god_class` — a class past the method-count threshold) appear here too, alongside the placement and hygiene findings. Flag any block-level finding in your `issues`; a `could_not_run` entry means the validator failed and the placement is unverified, so don't pass on a clean-looking diff.
 
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