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/code.iteration.html

@@ -0,0 +1,36 @@
+<ul>
+  <li>1</li>
+  <li>2</li>
+  <li>3</li>
+</ul>
+<ul>
+  <li class="item-0">1</li>
+  <li class="item-1">2</li>
+  <li class="item-2">3</li>
+</ul>
+<ul>
+  <li>1</li>
+  <li>2</li>
+  <li>3</li>
+</ul>
+<ul>
+  <li>1</li>
+  <li>2</li>
+  <li>3</li>
+</ul>
+<ul>
+  <li>1: a</li>
+  <li>2: a</li>
+  <li>3: a</li>
+  <li>1: b</li>
+  <li>2: b</li>
+  <li>3: b</li>
+  <li>1: c</li>
+  <li>2: c</li>
+  <li>3: c</li>
+</ul>
+<ul>
+  <li>1</li>
+  <li>2</li>
+  <li>3</li>
+</ul>