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

benchmarks/templates/simple-2.json

@@ -0,0 +1,20 @@
+{
+  "header": "Header",
+  "header2": "Header2",
+  "header3": "Header3",
+  "header4": "Header4",
+  "header5": "Header5",
+  "header6": "Header6",
+  "list": [
+    "1000000000",
+    "2",
+    "3",
+    "4",
+    "5",
+    "6",
+    "7",
+    "8",
+    "9",
+    "10"
+  ]
+}