v0.9.1

Fixes

• CLI: Fix Configuration Error: 'NoneType' object has no attribute lower' when running dsagent, dsagent chat, or dsagent run without --model or config. The effective model is now resolved with get_default_model() before validation. (#47, #48)

Other

• Validation: validate_configuration() now guards against None/empty model and raises a clear ConfigurationError instead of AttributeError.
• Workflow: Added .cursor/rules/workflow-branch-pr.mdc and updated AGENTS.md (issue → branch → fix → test → PR; no direct commits to main).
• Test: ConversationalAgentConfig default model is None (resolved at runtime).