Merge FASE 4: diagrams folder with 8 Mermaid + SVGs

Resolves two conflicts:

- docs/diagrams/README.md: FASE 3 created a placeholder, FASE 4 created the
  canonical content. Adopts FASE 4 content and updates the doc paths to the
  FASE 3 subfolder layout (architecture/, frameworks/, routing/, guides/).
- package.json: combined FASE 1's new scripts/build/ and scripts/check/ paths
  with FASE 4's new docs:render-diagrams script.

Post-merge fixes:
- Rewrites diagram link paths in the 7 subfolder docs from ./diagrams/X to
  ../diagrams/X (FASE 4 added flat-layout links before FASE 3's subfolder move).
- Adds the i18n-flow diagram link to docs/guides/I18N.md (auto-merge missed it).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -79,7 +79,10 @@ API routes follow a consistent pattern: `Route → CORS preflight → Zod body v
 ## Resilience Runtime State
 
 OmniRoute has three related but distinct temporary-failure mechanisms. Keep their
-scope separate when debugging routing behavior.
+scope separate when debugging routing behavior. See the
+[3-layer resilience diagram](./docs/diagrams/exported/resilience-3layers.svg)
+(source: [docs/diagrams/resilience-3layers.mmd](./docs/diagrams/resilience-3layers.mmd))
+for an at-a-glance map.
 
 ### Provider Circuit Breaker