docs: add AI generated visual architecture diagrams (#15)

* test(registry-check): add failing test for registry-fetch smoke check

- RED phase: test_registry_check.py covers all-200 success, one-404
  failure, network-unavailable distinction, HTTP 5xx errors, and CLI
  exit-code paths for the not-yet-implemented cas_evals.registry_check
- REQ-1.4.11

* feat(registry-check): implement registry-fetch smoke check module

- GREEN phase: check_registry_urls() performs live GETs against the Pages
  registry, raising RegistryCheckError naming the first failing path on
  non-200, HTTPError, or network-unavailable conditions
- main() is the python -m cas_evals.registry_check CLI entry point,
  checking index.json, v0.1/manifest.json, v0.1/common.schema.json, and
  v0.1/evaluation-result.schema.json by default; exits non-zero on failure
- Follows reference_product.py's urllib pattern: capped response reads
  (MAX_RESPONSE_BYTES), typed exception-to-domain-error translation
- REQ-1.4.11

* feat(contracts): verify registry-fetch smoke check + update vendored $id to resolvable Pages URL

- Update vendored v0.1.0 common/evaluation-result schema $id values from
  the dead schemas.coding-autopilot.dev namespace to the resolvable Pages
  registry URL, matching the portfolio-wide convention from cas-contracts
  plan 32-01
- Recompute sha256 in provenance.json for the re-vendored files
- Update verify_vendored_contract()'s two hardcoded $id equality checks
  to match the new value
- Wire a new registry-smoke CI job invoking cas_evals.registry_check
  against the live Pages registry, isolated from the offline verify matrix
  so a transient network failure doesn't block unrelated merges
- Regenerate releases/v0.2.0/manifest.json: its provenanceDigest is a
  sha256 of provenance.json, which changed as a direct consequence of the
  re-vendor above (Rule 3 auto-fix: this is a blocking downstream effect
  of the provenance.json edit required by this task, not new scope)
- REQ-1.4.11

* docs: add AI generated visual architecture diagrams

---------

Co-authored-by: Kim Harjamäki <kim.harjamaki@prosimo.fi>

Author: OgeonX-Ai

docs/architecture.md

@@ -30,6 +30,8 @@ Every per-case result generates an `EvaluationResult` conforming to the pinned `
 
 The following Mermaid diagram visualizes the evaluation pipeline across both offline and live modes.
 
+![Visual Diagram](assets/cas_evals_architecture.png)
+
 ```mermaid
 flowchart TD
     %% CLI and Input