test(T16): Bedrock + Vertex parser tests — fixtures + round-trips

[ogkranthi]

Summary

Closes T16 from BACKLOG.md.

What's added

tests/test_bedrock_parser.py (57 tests)

• Parse from bedrock-agent.json fixture: name, description, instruction, foundation model, agent/alias IDs
• Parse from cloudformation.yaml fixture (CFN-only directory): name, instruction, knowledge sources, tools from ActionGroups
• OpenAPI action groups → tools: multiple tools, parameters, auth variants (api_key, bearer, oauth2)
• guardrail-config.json → governance guardrails from topicPolicyConfig
• L1 heuristic guardrail extraction from instruction text (do not, never patterns)
• Round-trip: AgentIR → bedrock emit → bedrock parse (instruction, MCP tools, guardrails, sections, long instruction truncation)
• Edge cases: missing dirs, empty ActionGroups, truncation notice stripping, precedence rules

tests/test_vertex_parser.py (48 tests)

• Parse from agent.json fixture: name, description, system prompt, language, timestamps, extensions
• tools.json functionDeclarations → IR tools with parameters
• datastoreSpec → KnowledgeSource
• openApiFunctionDeclarations → openapi kind tool with endpoint
• Auth parsing: api_key, oauth2, bearer (service account)
• Guardrail heuristic extraction from instructions + Restrictions: section
• Round-trip: AgentIR → vertex emit → vertex parse (prompt, tools, guardrails, sections, display_name)
• Edge cases: missing agent.json, invalid JSON, empty tools, resource path inline tools, parse_agent_json() helper

Fixture files added

• tests/fixtures/bedrock/{bedrock-agent.json,cloudformation.yaml,openapi.json,guardrail-config.json}
• tests/fixtures/vertex/{agent.json,tools.json}

Test results

• 887 tests passing (was 782 → +105 new tests)
• Full suite: python -m pytest tests/ -q → 887 passed