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/sample_data/pug/test/regression-2436/index.test.js

@@ -0,0 +1,11 @@
+const pug = require('../../');
+
+test('#2436 - block with a same name extends from the same layout in nesting', () => {
+  const output = pug.renderFile(__dirname + '/issue1.pug', {pretty: true});
+  expect(output).toMatchSnapshot();
+});
+
+test('#2436 - block with a same name extends from different layout in nesting', () => {
+  const output = pug.renderFile(__dirname + '/issue2.pug', {pretty: true});
+  expect(output).toMatchSnapshot();
+});