feat(lexer): Scan alphanumerics & whitespace

tests/lexer/LexerScanTest.kt

@@ -53,6 +53,8 @@ class LexerScanTest {
         assertEquals(TokenType.ALPHANUMERIC, tokens[0].type, "Expected ALPHANUMERIC token, got ${tokens[0].type}")
         assertEquals(TokenType.EOF, tokens[1].type, "Expected EOF token, got ${tokens[1].type}")
 
+        assertEquals(0, tokens[0].position.line, "Expected line 0, got ${tokens[0].position.line}")
+        assertEquals(0, tokens[0].position.column, "Expected column 0, got ${tokens[0].position.column}")
         assertEquals(1, tokens[0].position.length, "Expected length 1, got ${tokens[0].position.length}")
     }
 
@@ -67,5 +69,17 @@ class LexerScanTest {
         assertEquals(TokenType.EOF, tokens[1].type, "Expected EOF token, got ${tokens[1].type}")
 
         assertEquals(4, tokens[0].position.length, "Expected length 4, got ${tokens[0].position.length}")
+
+        assertEquals("word", tokens[0].value, "Expected 'word', got ${tokens[0].value}")
+    }
+
+    @Test
+    fun scan_whitespace_returns_nothing() {
+        val lexer = Lexer(" ")
+        val tokens = lexer.scan()
+
+        assertEquals(1, tokens.size)
+
+        assertEquals(TokenType.EOF, tokens[0].type, "Expected EOF token, got ${tokens[0].type}")
     }
 }