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/layout.multi.append.prepend.block.html

@@ -0,0 +1,8 @@
+<p class="last prepend">Last prepend must appear at top</p>
+<p class="first prepend">Something prepended to content</p>
+<div class="content">Defined content</div>
+<p class="first append">Something appended to content</p>
+<p class="last append">Last append must be most last</p>
+<script src="foo.js"></script>
+<script src="/app.js"></script>
+<script src="jquery.js"></script>