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/attrs.js.html

@@ -0,0 +1,5 @@
+<a class="button" href="/user/5"></a><a class="button" href="/user/5"></a>
+<meta key="answer" value="42"/><a class="class1 class2"></a><a class="tag-class class1 class2"></a><a class="button" href="/user/5"></a><a class="button" href="/user/5"></a>
+<meta key="answer" value="42"/><a class="class1 class2"></a><a class="tag-class class1 class2"></a>
+<div id="5" foo="bar"></div>
+<div baz="baz"></div>