Add camera streaming guide with all access methods

Comprehensive documentation for accessing the DWARF camera streams:
- RTSP URLs and channels (ch0=tele, ch1=wide)
- The critical prerequisite: camera must be opened via WebSocket first
- ffmpeg commands for frame capture, timelapse, and video recording
- mpv and VLC usage with TCP transport
- Python/OpenCV integration example
- Troubleshooting common issues (black image, connection refused, VLC delay)
- Comparison of RTSP vs MJPEG modes across device models

💘 Generated with Crush

Assisted-by: Crush:glm-5.2

dwarfctl/internal/daemon/client.go

@@ -0,0 +1,112 @@
+package daemon
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"time"
+
+	"github.com/antitbone/dwarfctl/internal/odometry"
+)
+
+// Client is a thin HTTP client that talks to the daemon.
+type Client struct {
+	baseURL string
+	http    *http.Client
+}
+
+// NewClient creates a daemon client for the given address (e.g. "127.0.0.1:7777").
+func NewClient(addr string) *Client {
+	if addr == "" {
+		addr = DefaultAddr
+	}
+	return &Client{
+		baseURL: "http://" + addr,
+		http:    &http.Client{Timeout: 30 * time.Second},
+	}
+}
+
+// IsAlive checks if the daemon is reachable.
+func (c *Client) IsAlive() bool {
+	resp, err := c.http.Get(c.baseURL + "/health")
+	return err == nil && resp.StatusCode == 200
+}
+
+// Orientation returns the current cumulative orientation from the daemon.
+func (c *Client) Orientation() (odometry.Orientation, error) {
+	resp, err := c.http.Get(c.baseURL + "/orientation")
+	if err != nil {
+		return odometry.Orientation{}, err
+	}
+	defer resp.Body.Close()
+	var o odometry.Orientation
+	return o, json.NewDecoder(resp.Body).Decode(&o)
+}
+
+// Grab captures a frame. If path is empty, the daemon picks a temp path.
+// Returns the saved file path.
+func (c *Client) Grab(path string) (string, error) {
+	url := c.baseURL + "/grab"
+	if path != "" {
+		url += "?path=" + path
+	}
+	resp, err := c.http.Get(url)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 200 {
+		body, _ := io.ReadAll(resp.Body)
+		return "", fmt.Errorf("daemon: %s", body)
+	}
+	var result map[string]string
+	json.NewDecoder(resp.Body).Decode(&result)
+	return result["path"], nil
+}
+
+// Reset zeros the odometry.
+func (c *Client) Reset() error {
+	_, err := c.http.Post(c.baseURL+"/reset", "", nil)
+	return err
+}
+
+// Slew sends a joystick vector.
+func (c *Client) Slew(angle, length float64) error {
+	body, _ := json.Marshal(map[string]float64{"angle": angle, "length": length})
+	resp, err := c.http.Post(c.baseURL+"/slew", "application/json", bytes.NewReader(body))
+	if err != nil {
+		return err
+	}
+	resp.Body.Close()
+	return nil
+}
+
+// StopMotors stops all motors.
+func (c *Client) StopMotors() error {
+	_, err := c.http.Post(c.baseURL+"/stop", "", nil)
+	return err
+}
+
+// Camera opens or closes a camera.
+func (c *Client) Camera(action, cam string) error {
+	url := fmt.Sprintf("%s/camera?action=%s&cam=%s", c.baseURL, action, cam)
+	resp, err := c.http.Post(url, "", nil)
+	if err != nil {
+		return err
+	}
+	resp.Body.Close()
+	return nil
+}
+
+// SetFoV overrides the field of view.
+func (c *Client) SetFoV(h, v float64) error {
+	body, _ := json.Marshal(map[string]float64{"h": h, "v": v})
+	resp, err := c.http.Post(c.baseURL+"/fov", "application/json", bytes.NewReader(body))
+	if err != nil {
+		return err
+	}
+	resp.Body.Close()
+	return nil
+}