Just the $ (dollar sign) key. You can use A to move to the end of the line and switch to editing mode (Append). To jump the last non-blank character, you can press g then _ keys.
The opposite of A is I (Insert mode at beginning of line), as an aside. Pressing just the ^ will place your cursor at the first non-white-space character of the line.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…