feat: complete phase 3 -- OpenAPI auto-discovery, SSRF protection, tool generation

- SSRF protection: private IP blocking, DNS rebinding defense, redirect validation
- OpenAPI fetcher with SSRF guard, JSON/YAML auto-detection, 10MB limit
- Structural spec validator (3.0.x/3.1.x)
- Endpoint parser with $ref resolution, auto-generated operation IDs
- Heuristic + LLM endpoint classifier with Protocol interface
- Review API at /api/openapi (import, job status, classification CRUD, approve)
- @tool code generator + Agent YAML generator
- Import orchestrator (fetch -> validate -> parse -> classify pipeline)
- 125 new tests, 322 total passing, 93.23% coverage

backend/tests/unit/test_main.py

@@ -13,7 +13,7 @@ class TestMainModule:
         assert app.title == "Smart Support"
 
     def test_app_version(self) -> None:
-        assert app.version == "0.2.0"
+        assert app.version == "0.3.0"
 
     def test_agents_yaml_path_exists(self) -> None:
         assert AGENTS_YAML.name == "agents.yaml"