Cursor gets stuck when navigating up/down in textarea

**Description**
When using a textarea component, the cursor can get stuck and stop responding to up/down arrow key navigation. This might be due to off-by-one errors in the boundary condition checks within CursorDown() and CursorUp(). The comparison offset >= nli.CharWidth-1 exits the cursor positioning loop one iteration too early, preventing the cursor from reaching the correct column position on the target line.

Also when the content of a line (including spaces) exactly equals the textarea width, the wrap() function incorrectly creates an extra empty line. The condition >= width triggers a line wrap even when the content fits perfectly within the available width, producing a phantom blank line in the display. You can reach the last character using Ctrl+E, but not using down arrow key.

**Setup**
- OS: Any
- Shell: Any
- Terminal Emulator: Any
- Terminal Multiplexer: N/A
- Locale: N/A

**Steps**
1. Create a textarea with a specific width (e.g., 20 characters)
2. Type a line of text where the total content (text + spaces) adds up to exactly the textarea width
3. Observe an unexpected empty line appearing below the text
4. Observe the cursor gets stuck and does not move beyond this line

**Source Code**
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**Screenshots**

Refer the screenshot to see how the issue is recreated in story time example. Once setup, please try moving paste line 3 using down arrow key.