fix: add scoped error logging for lexer/parser errors

- Add std.log.scoped(.pugz) to template.zig and view_engine.zig
- Log detailed error info (code, line, column, message) when parsing fails
- Log template path context in ViewEngine on parse errors
- Remove debug print from lexer, use proper scoped logging instead
- Move benchmarks, docs, examples, playground, tests out of src/ to project root
- Update build.zig and documentation paths accordingly
- Bump version to 0.3.1

tests/check_list/classes.pug

@@ -0,0 +1,11 @@
+a(class=['foo', 'bar', 'baz'])
+
+
+
+a.foo(class='bar').baz
+
+
+
+a.foo-bar_baz
+
+a(class={foo: true, bar: false, baz: true})