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/helper.zig

@@ -0,0 +1,76 @@
+//! Test helper for Pugz engine
+//! Provides common utilities for template testing
+
+const std = @import("std");
+const pugz = @import("pugz");
+
+/// Normalizes HTML by removing indentation/formatting whitespace.
+/// This allows comparing pretty vs non-pretty output.
+fn normalizeHtml(allocator: std.mem.Allocator, html: []const u8) ![]const u8 {
+    var result = std.ArrayListUnmanaged(u8){};
+    var i: usize = 0;
+    var in_tag = false;
+    var last_was_space = false;
+
+    while (i < html.len) {
+        const c = html[i];
+
+        if (c == '<') {
+            // Strip trailing whitespace before tags
+            while (result.items.len > 0 and (result.items[result.items.len - 1] == ' ' or result.items[result.items.len - 1] == '\t')) {
+                _ = result.pop();
+            }
+            in_tag = true;
+            last_was_space = false;
+            try result.append(allocator, c);
+        } else if (c == '>') {
+            in_tag = false;
+            last_was_space = false;
+            try result.append(allocator, c);
+        } else if (c == '\n' or c == '\r' or c == ' ' or c == '\t') {
+            // Treat all whitespace (including newlines) uniformly
+            if (in_tag) {
+                // Preserve single space in tags for attribute separation
+                if (!last_was_space) {
+                    try result.append(allocator, ' ');
+                    last_was_space = true;
+                }
+            } else {
+                // Outside tags: skip leading whitespace after >
+                if (result.items.len > 0 and result.items[result.items.len - 1] != '>') {
+                    if (!last_was_space) {
+                        try result.append(allocator, ' ');
+                        last_was_space = true;
+                    }
+                }
+            }
+            i += 1;
+            continue;
+        } else {
+            last_was_space = false;
+            try result.append(allocator, c);
+        }
+        i += 1;
+    }
+
+    return result.toOwnedSlice(allocator);
+}
+
+/// Expects the template to produce the expected output when rendered with the given data.
+/// Uses arena allocator for automatic cleanup.
+/// Normalizes whitespace/formatting so pretty-print differences don't cause failures.
+pub fn expectOutput(template: []const u8, data: anytype, expected: []const u8) !void {
+    var arena = std.heap.ArenaAllocator.init(std.testing.allocator);
+    defer arena.deinit();
+    const allocator = arena.allocator();
+
+    const raw_result = try pugz.renderTemplate(allocator, template, data);
+    const result = std.mem.trimRight(u8, raw_result, "\n");
+    const expected_trimmed = std.mem.trimRight(u8, expected, "\n");
+
+    // Normalize both for comparison (ignores pretty-print differences)
+    const norm_result = try normalizeHtml(allocator, result);
+    const norm_expected = try normalizeHtml(allocator, expected_trimmed);
+
+    try std.testing.expectEqualStrings(norm_expected, norm_result);
+}