feat(agents): Add Create/Delete Agent functionality

Backend:
- Added POST /city/agents endpoint for creating agents
- Added DELETE /city/agents/{id} endpoint for soft-deleting agents
- Added CreateAgentRequest, CreateAgentResponse, DeleteAgentResponse models

Frontend:
- Added '+ Новий агент' button on /agents page
- Created /agents/new page with full agent creation form
- Added 'Видалити агента' button in agent Identity tab (Danger Zone)

Features:
- Auto-generate slug from display_name
- Support for all agent fields: kind, role, model, node, district, microdao
- Color picker for agent color
- Visibility toggles (is_public, is_orchestrator)
- Soft delete with confirmation dialog

services/city-service/models_city.py

@@ -579,6 +579,48 @@ class MicrodaoOption(BaseModel):
     is_active: bool = True
 
 
+# =============================================================================
+# Agent Management (Create/Delete)
+# =============================================================================
+
+class CreateAgentRequest(BaseModel):
+    """Request to create a new agent"""
+    slug: str
+    display_name: str
+    kind: str = "assistant"  # assistant, orchestrator, specialist, civic
+    role: Optional[str] = None
+    model: Optional[str] = None
+    node_id: Optional[str] = None
+    home_node_id: Optional[str] = None
+    home_microdao_id: Optional[str] = None
+    district: Optional[str] = None
+    primary_room_slug: Optional[str] = None
+    avatar_url: Optional[str] = None
+    color_hint: Optional[str] = None
+    is_public: bool = False
+    is_orchestrator: bool = False
+    priority: str = "medium"
+
+
+class CreateAgentResponse(BaseModel):
+    """Response after creating an agent"""
+    id: str
+    slug: str
+    display_name: str
+    kind: str
+    node_id: Optional[str] = None
+    home_microdao_id: Optional[str] = None
+    district: Optional[str] = None
+    created_at: datetime
+
+
+class DeleteAgentResponse(BaseModel):
+    """Response after deleting an agent"""
+    ok: bool
+    message: str
+    agent_id: str
+
+
 # =============================================================================
 # Visibility Updates (Task 029)
 # =============================================================================

services/city-service/routes_city.py

@@ -47,7 +47,10 @@ from models_city import (
     MicrodaoRoomUpdate,
     AttachExistingRoomRequest,
     SwapperModel,
-    NodeSwapperDetail
+    NodeSwapperDetail,
+    CreateAgentRequest,
+    CreateAgentResponse,
+    DeleteAgentResponse
 )
 import repo_city
 from common.redis_client import PresenceRedis, get_redis
@@ -2535,6 +2538,120 @@ async def get_agents():
         raise HTTPException(status_code=500, detail="Failed to get agents")
 
 
+@router.post("/agents", response_model=CreateAgentResponse)
+async def create_agent(body: CreateAgentRequest):
+    """
+    Створити нового агента
+    """
+    try:
+        pool = await repo_city.get_pool()
+        
+        # Check if slug already exists
+        existing = await pool.fetchrow(
+            "SELECT id FROM agents WHERE id = $1 OR slug = $1",
+            body.slug
+        )
+        if existing:
+            raise HTTPException(status_code=400, detail=f"Agent with slug '{body.slug}' already exists")
+        
+        # Generate ID from slug
+        agent_id = body.slug
+        
+        # Insert agent
+        row = await pool.fetchrow("""
+            INSERT INTO agents (
+                id, slug, display_name, kind, role, model,
+                node_id, home_node_id, home_microdao_id, district,
+                primary_room_slug, avatar_url, color_hint,
+                is_public, is_orchestrator, priority,
+                created_at, updated_at
+            ) VALUES (
+                $1, $2, $3, $4, $5, $6,
+                $7, $8, $9, $10,
+                $11, $12, $13,
+                $14, $15, $16,
+                NOW(), NOW()
+            )
+            RETURNING id, slug, display_name, kind, node_id, home_microdao_id, district, created_at
+        """,
+            agent_id,
+            body.slug,
+            body.display_name,
+            body.kind,
+            body.role,
+            body.model,
+            body.node_id,
+            body.home_node_id or body.node_id,
+            body.home_microdao_id,
+            body.district,
+            body.primary_room_slug,
+            body.avatar_url,
+            body.color_hint,
+            body.is_public,
+            body.is_orchestrator,
+            body.priority
+        )
+        
+        logger.info(f"Created agent: {agent_id}")
+        
+        return CreateAgentResponse(
+            id=row["id"],
+            slug=row["slug"],
+            display_name=row["display_name"],
+            kind=row["kind"],
+            node_id=row["node_id"],
+            home_microdao_id=row["home_microdao_id"],
+            district=row["district"],
+            created_at=row["created_at"]
+        )
+    
+    except HTTPException:
+        raise
+    except Exception as e:
+        logger.error(f"Failed to create agent: {e}")
+        raise HTTPException(status_code=500, detail=f"Failed to create agent: {str(e)}")
+
+
+@router.delete("/agents/{agent_id}", response_model=DeleteAgentResponse)
+async def delete_agent(agent_id: str):
+    """
+    Видалити агента (soft delete - встановлює is_archived=true, deleted_at=now())
+    """
+    try:
+        pool = await repo_city.get_pool()
+        
+        # Check if agent exists
+        existing = await pool.fetchrow(
+            "SELECT id, display_name FROM agents WHERE id = $1 AND deleted_at IS NULL",
+            agent_id
+        )
+        if not existing:
+            raise HTTPException(status_code=404, detail=f"Agent '{agent_id}' not found")
+        
+        # Soft delete
+        await pool.execute("""
+            UPDATE agents
+            SET is_archived = true,
+                deleted_at = NOW(),
+                updated_at = NOW()
+            WHERE id = $1
+        """, agent_id)
+        
+        logger.info(f"Deleted (archived) agent: {agent_id}")
+        
+        return DeleteAgentResponse(
+            ok=True,
+            message=f"Agent '{existing['display_name']}' has been archived",
+            agent_id=agent_id
+        )
+    
+    except HTTPException:
+        raise
+    except Exception as e:
+        logger.error(f"Failed to delete agent: {e}")
+        raise HTTPException(status_code=500, detail=f"Failed to delete agent: {str(e)}")
+
+
 @router.get("/agents/online", response_model=List[AgentPresence])
 async def get_online_agents():
     """