fix(handlers): check rows.Err() after iteration in 4 list handlers

Four HTTP handlers iterated sql.Rows without calling rows.Err() after
the loop, silently swallowing mid-stream Postgres/network errors:

- ListEvents / ListByWorkspace (events.go)
- ListChannels (channels.go)
- HandleTelegramWebhook (channels.go)
- List (memory.go)

Added rows.Err() checks after each loop so iteration errors are logged
rather than silently truncating results returned to callers.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

workspace-server/internal/handlers/channels.go

@@ -104,6 +104,9 @@ func (h *ChannelHandler) List(c *gin.Context) {
 		}
 		result = append(result, entry)
 	}
+	if err := rows.Err(); err != nil {
+		log.Printf("Channels list rows error: %v", err)
+	}
 
 	c.JSON(http.StatusOK, result)
 }
@@ -514,6 +517,9 @@ func (h *ChannelHandler) Webhook(c *gin.Context) {
 			candidates = append(candidates, row)
 		}
 	}
+	if err := rows.Err(); err != nil {
+		log.Printf("Channels: telegram webhook rows error: %v", err)
+	}
 
 	if targetSlug != "" {
 		// [slug] routing — match against config username (lowercased)

workspace-server/internal/handlers/events.go

@@ -49,6 +49,9 @@ func (h *EventsHandler) List(c *gin.Context) {
 			"created_at":   createdAt,
 		})
 	}
+	if err := rows.Err(); err != nil {
+		log.Printf("Events rows error: %v", err)
+	}
 	c.JSON(http.StatusOK, events)
 }
 
@@ -87,5 +90,8 @@ func (h *EventsHandler) ListByWorkspace(c *gin.Context) {
 			"created_at":   createdAt,
 		})
 	}
+	if err := rows.Err(); err != nil {
+		log.Printf("Events rows error (workspace %s): %v", workspaceID, err)
+	}
 	c.JSON(http.StatusOK, events)
 }

workspace-server/internal/handlers/memory.go

@@ -54,6 +54,9 @@ func (h *MemoryHandler) List(c *gin.Context) {
 		entry.Value = json.RawMessage(value)
 		entries = append(entries, entry)
 	}
+	if err := rows.Err(); err != nil {
+		log.Printf("Memory list rows error: %v", err)
+	}
 
 	c.JSON(http.StatusOK, entries)
 }