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/test/cases/attrs.colon.pug

@@ -0,0 +1,9 @@
+//- Tests for using a colon-prefexed attribute (typical when using short-cut for Vue.js `v-bind`)
+div(:my-var="model")
+span(v-for="item in items" :key="item.id" :value="item.name")
+span(
+  v-for="item in items"
+  :key="item.id"
+  :value="item.name"
+)
+a(:link="goHere" value="static" :my-value="dynamic" @click="onClick()" :another="more") Click Me!