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/debug_test.zig

@@ -0,0 +1,46 @@
+const std = @import("std");
+const lexer_mod = @import("../lexer.zig");
+const parser_mod = @import("../parser.zig");
+const ast = @import("../ast.zig");
+
+test "debug block expansion" {
+    const alloc = std.testing.allocator;
+    
+    const pug = 
+        \\ul
+        \\  li.list-item: .foo: #bar baz
+    ;
+    
+    var lexer = lexer_mod.Lexer.init(alloc, pug);
+    const tokens = try lexer.tokenize();
+    
+    var parser = parser_mod.Parser.init(alloc, tokens);
+    const doc = try parser.parse();
+    
+    // Print structure
+    std.debug.print("\n", .{});
+    for (doc.nodes) |node| {
+        printNode(node, 0);
+    }
+}
+
+fn printNode(node: ast.Node, depth: usize) void {
+    var i: usize = 0;
+    while (i < depth * 2) : (i += 1) {
+        std.debug.print(" ", .{});
+    }
+    switch (node) {
+        .element => |elem| {
+            std.debug.print("element: {s} is_inline={} children={d}", .{elem.tag, elem.is_inline, elem.children.len});
+            if (elem.inline_text != null) {
+                std.debug.print(" (has inline_text)", .{});
+            }
+            std.debug.print("\n", .{});
+            for (elem.children) |child| {
+                printNode(child, depth + 1);
+            }
+        },
+        .text => |_| std.debug.print("text\n", .{}),
+        else => std.debug.print("other\n", .{}),
+    }
+}