lib.Uri: Fix stale cache in __new_with_path()

__new_with_path() builds the new Uri by deep-copying self and then
replacing __string. A deep copy, however, also carries over any
cached_property values that were already computed on self (e.g. __p,
path, scheme, full), so once __string changes, they stay stale: for a
Uri on which any of those properties had been accessed before,
new_add_path() and new_replace_path() returned objects whose
to_string() showed the new string while path(), hostname(), full() and
friends still described the old one.

Build a fresh instance with object.__new__() and initialize its three
basic attributes instead of copying, so no computed cached state can
be inherited.

Assisted-by: unsloth/Qwen3.8-27B-GGUF:Q4_K_M and pi.dev
Signed-off-by: Jan Lindemann <jan@janware.com>

src/python/jw/pkg/lib/Uri.py

@@ -1,7 +1,5 @@
 from __future__ import annotations
 
-import copy
-
 from functools import cached_property
 from typing import TYPE_CHECKING, override
 
@@ -149,7 +147,10 @@ class Uri:
         )
 
     def __new_with_path(self, base: str, path: str) -> Self:
-        ret = copy.deepcopy(self)
+        # -- Build a fresh instance rather than copying self: a copy would
+        # inherit computed cached_property values (e.g. __p, path, full),
+        # which would go stale as soon as __string is replaced below.
+        ret = object.__new__(type(self))
         ret.__string = base
         ret.__username = None
         ret.__password = None