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-1.json

@@ -0,0 +1,19 @@
+{
+  "name": "George Washington",
+  "messageCount": 999,
+  "colors": [
+    "red",
+    "green",
+    "blue",
+    "yellow",
+    "orange",
+    "pink",
+    "black",
+    "white",
+    "beige",
+    "brown",
+    "cyan",
+    "magenta"
+  ],
+  "primary": true
+}