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/sample_data/pug/examples/rss.js

@@ -0,0 +1,28 @@
+/**
+ * Module dependencies.
+ */
+
+var pug = require('../'),
+  path = __dirname + '/rss.pug',
+  str = require('fs').readFileSync(path, 'utf8'),
+  fn = pug.compile(str, {filename: path, pretty: true});
+
+var items = [];
+
+items.push({
+  title: 'Example',
+  description: 'Something',
+  link: 'http://google.com',
+});
+items.push({
+  title: 'LearnBoost',
+  description: 'Cool',
+  link: 'http://learnboost.com',
+});
+items.push({
+  title: 'Express',
+  description: 'Cool',
+  link: 'http://expressjs.com',
+});
+
+console.log(fn({items: items}));