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/check_list/each.else.pug

@@ -0,0 +1,43 @@
+
+- var users = []
+
+ul
+  for user in users
+    li= user.name
+  else
+    li no users!
+
+
+- var users = [{ name: 'tobi', friends: ['loki'] }, { name: 'loki' }]
+
+if users
+  ul
+    for user in users
+      li= user.name
+    else
+      li no users!
+
+- var user = { name: 'tobi', age: 10 }
+
+ul
+  each val, key in user
+    li #{key}: #{val}
+  else
+    li user has no details!
+
+- var user = {}
+
+ul
+  each prop, key in user
+    li #{key}: #{val}
+  else
+    li user has no details!
+
+- var user = Object.create(null)
+- user.name = 'tobi'
+
+ul
+  each val, key in user
+    li #{key}: #{val}
+  else
+    li user has no details!