feat(agents): add category and display fields to AgentType model

Add 6 new fields to AgentType for better organization and UI display:
- category: enum for grouping (development, design, quality, etc.)
- icon: Lucide icon identifier for UI
- color: hex color code for visual distinction
- sort_order: display ordering within categories
- typical_tasks: list of tasks the agent excels at
- collaboration_hints: agent slugs that work well together

Backend changes:
- Add AgentTypeCategory enum to enums.py
- Update AgentType model with 6 new columns and indexes
- Update schemas with validators for new fields
- Add category filter and /grouped endpoint to routes
- Update CRUD with get_grouped_by_category method
- Update seed data with categories for all 27 agents
- Add migration 0007

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/app/models/syndarix/enums.py

@@ -167,3 +167,29 @@ class SprintStatus(str, PyEnum):
     IN_REVIEW = "in_review"
     COMPLETED = "completed"
     CANCELLED = "cancelled"
+
+
+class AgentTypeCategory(str, PyEnum):
+    """
+    Category classification for agent types.
+
+    Used for grouping and filtering agents in the UI.
+
+    DEVELOPMENT: Product, project, and engineering roles
+    DESIGN: UI/UX and design research roles
+    QUALITY: QA and security engineering
+    OPERATIONS: DevOps and MLOps
+    AI_ML: Machine learning and AI specialists
+    DATA: Data science and engineering
+    LEADERSHIP: Technical leadership roles
+    DOMAIN_EXPERT: Industry and domain specialists
+    """
+
+    DEVELOPMENT = "development"
+    DESIGN = "design"
+    QUALITY = "quality"
+    OPERATIONS = "operations"
+    AI_ML = "ai_ml"
+    DATA = "data"
+    LEADERSHIP = "leadership"
+    DOMAIN_EXPERT = "domain_expert"