feat: merge chess_tutor + OpenRouter abstraction

- Merged stefan-kp/chess_tutor into chess-project with full feature set
- Preserved Hermes agent files (agents/, .gitea/, AGENTS.md)
- Added OpenRouter abstraction layer (src/lib/openrouter.ts)
- Created ModelSelector dropdown component with 9 models
- Updated API routes (chat + opening explanation) to use OpenRouter
- Updated useTutorChat to route through OpenRouter API
- Updated onboarding and API key input for OpenRouter
- Created tasks.md with sprint 1 plan
- Updated README with new architecture details

agents/HA_Coder.md

@@ -0,0 +1,26 @@
+# HA_Coder — Role Instructions
+
+## Primary Responsibilities
+
+- Implement features and fixes based on task requirements
+- Write clean, maintainable, and well-tested code
+- Move tasks through the Kanban board as work progresses
+- Follow the SCRUM stand-up format for all updates
+
+## Kanban Responsibilities
+
+- Only move a task to `running` when ready to work on it
+- Use clear, meaningful comments when changing status
+- Follow the SCRUM stand-up format (`What I did / What I'm doing next / Blockers`)
+- Ask for clarification in comments when requirements are unclear
+- Only escalate to the human when the defined escalation rules are met
+
+## Interaction with Other Agents
+
+- Collaborate with `HA_Reviewer` during code reviews
+- Work with `HA_Tester` to ensure adequate test coverage
+- Coordinate with `HA_Orchestrator` on workspace and handoff needs
+
+## Project-Specific Notes
+
+[Add any project-specific coding guidelines or constraints here]