Initial commit: Pugz - Pug-like HTML template engine in Zig

Features:
- Lexer with indentation tracking and raw text block support
- Parser producing AST from token stream
- Runtime with variable interpolation, conditionals, loops
- Mixin support (params, defaults, rest args, block content, attributes)
- Template inheritance (extends/block/append/prepend)
- Plain text (piped, dot blocks, literal HTML)
- Tag interpolation (#[tag text])
- Block expansion with colon
- Self-closing tags (void elements + explicit /)
- Case/when statements
- Comments (rendered and silent)

All 113 tests passing.

src/tests/mixin_debug_test.zig

@@ -0,0 +1,18 @@
+const std = @import("std");
+const pugz = @import("pugz");
+
+test "debug mixin tokens" {
+    const allocator = std.testing.allocator;
+    
+    const template = "+pet('cat')";
+    
+    var lexer = pugz.Lexer.init(allocator, template);
+    defer lexer.deinit();
+    
+    const tokens = try lexer.tokenize();
+    
+    std.debug.print("\n=== Tokens for: {s} ===\n", .{template});
+    for (tokens, 0..) |tok, i| {
+        std.debug.print("{d}: {s} = '{s}'\n", .{i, @tagName(tok.type), tok.value});
+    }
+}