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/README.md

@@ -0,0 +1,15 @@
+# Running Tests
+
+To run tests (with node.js installed) you must complete 2 steps.
+
+## 1 Install dependencies
+
+```
+npm install
+```
+
+## 2 Run tests
+
+```
+npm test
+```