feat(videochat): implement LiveKit integration for video chat functionality

- Add LiveKit client setup and token generation for room access.
- Implement room management functions including CreateRoom, OpenRoom, ListRooms, and DeleteRoom.
- Introduce participant management with ListParticipants and RemoveParticipant functions.
- Create tests for room and participant management, ensuring proper authentication and authorization.
- Add error handling for LiveKit API interactions.
- Define data structures for room metadata and token responses.
- Implement status endpoint for service availability check.

videochat/tokens.go

@@ -0,0 +1,57 @@
+package videochat
+
+import (
+	"context"
+
+	"encore.dev/beta/auth"
+	"encore.dev/beta/errs"
+)
+
+type TokenParams struct {
+	RoomName string `json:"room_name"`
+}
+
+type TokenResponse struct {
+	OwnerID          string `json:"owner_id"`
+	Role             string `json:"role"`
+	ServerURL        string `json:"server_url"`
+	ParticipantToken string `json:"participant_token" encore:"sensitive"`
+	RoomName         string `json:"room_name"`
+	Identity         string `json:"identity"`
+	ExpiresIn        int64  `json:"expires_in"`
+}
+
+// CreateToken grants the authenticated user access to an existing room by name.
+//
+//encore:api auth method=POST path=/videochat/token
+func CreateToken(ctx context.Context, p *TokenParams) (*TokenResponse, error) {
+	uid, ok := auth.UserID()
+	if !ok {
+		return nil, &errs.Error{Code: errs.Unauthenticated, Message: "must be logged in"}
+	}
+	if err := validateRoomName(p.RoomName); err != nil {
+		return nil, err
+	}
+	client, serverURL, err := liveKitClient()
+	if err != nil {
+		return nil, err
+	}
+	ctx, cancel := context.WithTimeout(ctx, apiTimeout)
+	defer cancel()
+	_, metadata, err := findBroadcast(ctx, client, p.RoomName)
+	if err != nil {
+		return nil, err
+	}
+	token, err := signJoinToken(secrets.LiveKitAPIKey, secrets.LiveKitAPISecret, string(uid), p.RoomName, metadata.OwnerID == string(uid))
+	if err != nil {
+		return nil, errs.WrapCode(err, errs.Internal, "failed to generate LiveKit token")
+	}
+	role := "viewer"
+	if metadata.OwnerID == string(uid) {
+		role = "owner"
+	}
+	return &TokenResponse{OwnerID: metadata.OwnerID, Role: role,
+		ServerURL: serverURL, ParticipantToken: token, RoomName: p.RoomName,
+		Identity: string(uid), ExpiresIn: int64(tokenTTL.Seconds()),
+	}, nil
+}