Broad bug hunt: auth flow, WS edge cases, and build hygiene.

Scope API auth to /api/v1, fix dashboard WebSocket 401s, session login in Calibrate, safe agent naming, reconnect races, and remove corrupt ollama/main.go.

agent/client/client.go

@@ -241,6 +241,9 @@ func (c *AgentClient) handleCommand(action string, tailLines int, command, path,
 			}
 		}()
 	case "get_log":
+		if tailLines <= 0 {
+			tailLines = 300
+		}
 		content, err := readLogTail(c.cfg, tailLines)
 		if err != nil {
 			c.sendCommandResult(action, false, err.Error())