Add domain agent catalog alignment and coverage

[2-Coatl]

Summary

• create domain-specific agent fichas (ApiAgent, UiAgent, InfrastructureAgent, DocsAgent, ScriptsAgent) and document their ExecPlan relationships
• update agent governance README, SDLC guide, and multi-LLM ExecPlan to map repository domains to agents
• introduce EXECPLAN_agents_domain_alignment and extend documentation alignment tests to cover the new catalog

Testing

• pytest scripts/coding/tests/ai/orchestrators/test_codex_mcp_workflow.py
• pytest docs/testing/test_documentation_alignment.py

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Codex Task