Assign readable ticket keys from project code and sequence.

Replace UUID-looking sync labels in TUI and web with keys like TAS-1,
while keeping the remote UUID for task-master matching.

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/project/project.go

@@ -4,5 +4,6 @@ package project
 type Project struct {
 	ID      string `json:"id"`
 	Name    string `json:"name"`
+	Code    string `json:"code,omitempty"`
 	GroupID string `json:"groupId,omitempty"`
 }