Add in-progress state to tasks

Introduce IN_PROGRESS as a new task state between TODO and DONE across
the full stack: database enum, Go backend, GraphQL, MCP, and frontend.

The task state icon now cycles forward on click (TODO → IN_PROGRESS →
DONE → TODO), and the action dropdown provides explicit "Move to"
options for any state transition. The "All" tab supports drag-and-drop
between state sections to change a task's state.

Signed-off-by: Sacha Al Himdani <sacha@getprobo.com>

e2e/console/task_test.go

@@ -320,6 +320,7 @@ func TestTask_StateEnum(t *testing.T) {
 
 	states := []string{
 		"TODO",
+		"IN_PROGRESS",
 		"DONE",
 	}