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/alembic/versions/0007_add_agent_type_category_fields.py

@@ -0,0 +1,90 @@
+"""Add category and display fields to agent_types table
+
+Revision ID: 0007
+Revises: 0006
+Create Date: 2026-01-06
+
+This migration adds:
+- category: String(50) for grouping agents by role type
+- icon: String(50) for Lucide icon identifier
+- color: String(7) for hex color code
+- sort_order: Integer for display ordering within categories
+- typical_tasks: JSONB list of tasks this agent excels at
+- collaboration_hints: JSONB list of agent slugs that work well together
+"""
+
+from collections.abc import Sequence
+
+import sqlalchemy as sa
+from alembic import op
+from sqlalchemy.dialects import postgresql
+
+# revision identifiers, used by Alembic.
+revision: str = "0007"
+down_revision: str | None = "0006"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    """Add category and display fields to agent_types table."""
+    # Add new columns
+    op.add_column(
+        "agent_types",
+        sa.Column("category", sa.String(length=50), nullable=True),
+    )
+    op.add_column(
+        "agent_types",
+        sa.Column("icon", sa.String(length=50), nullable=True, server_default="bot"),
+    )
+    op.add_column(
+        "agent_types",
+        sa.Column(
+            "color", sa.String(length=7), nullable=True, server_default="#3B82F6"
+        ),
+    )
+    op.add_column(
+        "agent_types",
+        sa.Column("sort_order", sa.Integer(), nullable=False, server_default="0"),
+    )
+    op.add_column(
+        "agent_types",
+        sa.Column(
+            "typical_tasks",
+            postgresql.JSONB(astext_type=sa.Text()),
+            nullable=False,
+            server_default="[]",
+        ),
+    )
+    op.add_column(
+        "agent_types",
+        sa.Column(
+            "collaboration_hints",
+            postgresql.JSONB(astext_type=sa.Text()),
+            nullable=False,
+            server_default="[]",
+        ),
+    )
+
+    # Add indexes for category and sort_order
+    op.create_index("ix_agent_types_category", "agent_types", ["category"])
+    op.create_index("ix_agent_types_sort_order", "agent_types", ["sort_order"])
+    op.create_index(
+        "ix_agent_types_category_sort", "agent_types", ["category", "sort_order"]
+    )
+
+
+def downgrade() -> None:
+    """Remove category and display fields from agent_types table."""
+    # Drop indexes
+    op.drop_index("ix_agent_types_category_sort", table_name="agent_types")
+    op.drop_index("ix_agent_types_sort_order", table_name="agent_types")
+    op.drop_index("ix_agent_types_category", table_name="agent_types")
+
+    # Drop columns
+    op.drop_column("agent_types", "collaboration_hints")
+    op.drop_column("agent_types", "typical_tasks")
+    op.drop_column("agent_types", "sort_order")
+    op.drop_column("agent_types", "color")
+    op.drop_column("agent_types", "icon")
+    op.drop_column("agent_types", "category")