feat: add operation registry generator, robust YAML/JSON parsing, and 50+ real-world OpenAPI specs

Add a new registry generator that emits static operation metadata (method, path, params, body,
response schema) for CLI/proxy routing use cases. Support registry_only mode to skip types/client
generation entirely.

Harden spec parsing: handle YAML integers exceeding i64/u64 range, add lossy JSON fallback,
and improve $ref schema name extraction for non-standard ref patterns. Make Info.version optional
since some specs omit it.

Include 50+ real-world OpenAPI specs (Stripe, GitHub, Cloudflare, etc.) with download script
and batch test harness for validation coverage.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: lightsofapollo

examples/complete_workflow.rs

@@ -311,6 +311,8 @@ fn demonstrate_rust_api(
         streaming_config: None,
         nullable_field_overrides: std::collections::BTreeMap::new(),
         schema_extensions: vec![],
+        enable_registry: false,
+        registry_only: false,
     };
 
     // Generate code