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/shadowed-block/__snapshots__/index.test.js.snap

@@ -0,0 +1,5 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`layout with shadowed block 1`] = `"<!-- layout.pug: root--><!-- index.pug: shadowed-->"`;
+
+exports[`layout with shadowed block 2`] = `"<!-- layout.pug: root--><!-- index.pug: shadowed-->"`;

tests/sample_data/pug/test/shadowed-block/base.pug

@@ -0,0 +1,4 @@
+block root
+  // base.pug: root
+  block shadowed
+    // base.pug: shadowed

tests/sample_data/pug/test/shadowed-block/index.pug

@@ -0,0 +1,4 @@
+extends ./layout.pug
+
+block shadowed
+  // index.pug: shadowed

tests/sample_data/pug/test/shadowed-block/index.test.js

@@ -0,0 +1,10 @@
+const pug = require('../../');
+
+test('layout with shadowed block', () => {
+  const outputWithAjax = pug.renderFile(__dirname + '/index.pug', {ajax: true});
+  const outputWithoutAjax = pug.renderFile(__dirname + '/index.pug', {
+    ajax: false,
+  });
+  expect(outputWithAjax).toMatchSnapshot();
+  expect(outputWithoutAjax).toMatchSnapshot();
+});

tests/sample_data/pug/test/shadowed-block/layout.pug

@@ -0,0 +1,6 @@
+extends ./base.pug
+
+block root
+  // layout.pug: root
+  block shadowed
+    // layout.pug: shadowed