Fix NO-BREAK SPACE (U+00A0) column width calculation (#448)

* Fix NO-BREAK SPACE (U+00A0) column width calculation

The condition `irune <= 0xA0` incorrectly treated U+00A0 (NO-BREAK SPACE)
as non-printable, returning width -1. This caused cursor positioning
issues in applications that use NBSP in their output.

Changed to `irune < 0xA0` so that NO-BREAK SPACE correctly returns
width 1 (handled by the default case at end of function), matching
the behavior of regular space (U+0020).

* Add test for NO-BREAK SPACE (U+00A0) width

Verifies that NBSP has width 1 and cursor positioning works correctly
when NBSP is used (e.g., after prompt characters like in Claude Code).

Author: kuzmeech

Sources/SwiftTerm/Utilities.swift

@@ -331,8 +331,9 @@ struct UnicodeUtil {
         if irune < 0x7f {
             return 1
         }
-	// more non-printable characters
-        if irune <= 0xA0 {
+	// C1 control characters (0x7F-0x9F) return -1
+        // Note: 0xA0 (NO-BREAK SPACE) is excluded - it should have width 1
+        if irune < 0xA0 {
             return -1
         }
 //        if irune < 127 {

Tests/SwiftTermTests/UnicodeTests.swift

@@ -274,5 +274,30 @@ final class SwiftTermUnicode {
         #expect(line == "\(sequence)X")
     }
 
+    @Test func testNoBreakSpaceWidth() {
+        let h = HeadlessTerminal (queue: SwiftTermTests.queue) { exitCode in }
+        let t = h.terminal!
+
+        // Test NO-BREAK SPACE (U+00A0) positioning
+        // NBSP should have width 1, same as regular space
+        // This is important for applications like Claude Code that use NBSP after prompt
+        t.feed (text: ">\u{00A0}x")  // > + NBSP + x
+
+        // '>' at col 0 (width 1)
+        #expect(t.getCharacter(col: 0, row: 0) == ">")
+        #expect(t.getCharData(col: 0, row: 0)?.width == 1)
+
+        // NBSP at col 1 (width 1, NOT -1)
+        #expect(t.getCharacter(col: 1, row: 0) == "\u{00A0}")
+        #expect(t.getCharData(col: 1, row: 0)?.width == 1)
+
+        // 'x' at col 2 (width 1)
+        #expect(t.getCharacter(col: 2, row: 0) == "x")
+        #expect(t.getCharData(col: 2, row: 0)?.width == 1)
+
+        // Cursor should be at column 3
+        #expect(t.buffer.x == 3)
+    }
+
 }
 #endif