fix: add tab character to whitespace skipping in nextToken parser

The nextToken function in wren_compiler.c previously only skipped spaces and carriage returns when advancing past whitespace, causing tab characters to be treated as non-whitespace tokens. This change adds '\t' to the whitespace check in both the initial case statement and the peekChar loop, ensuring tabs are properly skipped like other whitespace characters. A new test file test/whitespace.wren is added to verify correct handling of tabs in various indentation patterns and inline code positions.

test/whitespace.wren

@@ -0,0 +1,26 @@
+// No indent
+IO.print("ok") // expect: ok
+
+// Indent with space
+  IO.print("ok") // expect: ok
+
+// Indent with tab
+	IO.print("ok") // expect: ok
+
+// Indent with space then tab
+  	IO.print("ok") // expect: ok
+
+// Indent with tab then space
+	  IO.print("ok") // expect: ok
+
+// Indent with mixed tab and space
+  	  	IO.print("ok") // expect: ok
+
+// Space in with code
+IO . print ( "ok" ) // expect: ok
+
+// Tab in with code
+IO	.	print	(	"ok"	) // expect: ok
+
+// Tab and space mixed in with code
+IO	 . 	print 	(	 "ok" 	) // expect: ok