fix: resolve relative paths in includes/extends from current file directory

- Rename parseWithIncludes to parseTemplate for clarity
- Add resolveRelativePath to handle ../path and ./path relative to current file
- Paths without ./ or ../ prefix are relative to views_dir root (Pug convention)
- Fix duplicate include processing when extends loads parent with includes
- Add tests for relative path resolution
- All paths still validated against views_dir root (security unchanged)

build.zig.zon

@@ -1,6 +1,6 @@
 .{
     .name = .pugz,
-    .version = "0.3.2",
+    .version = "0.3.3",
     .fingerprint = 0x822db0790e17621d, // Changing this has security and trust implications.
     .minimum_zig_version = "0.15.2",
     .dependencies = .{},