Migrate remaining Component() callers to Element; delete the shim

The legacy back-compat ``Component(tag_name=...)`` function (a thin
string-returning wrapper over ``Element``) was the last piece of the
pre-node-tree API. Migrate its ~18 call sites across the views to the node
builders and remove it:

- stats_content.py: the table helpers now use the whitelisted ``Td`` / ``Th``
  / ``Tr`` builders and ``Element`` for table/tbody/thead/h1; helper return
  types are ``Node``.
- auth.py / statuschange.py / game.py / purchase.py: the hand-built
  ``<form>`` / ``<button>`` / ``<h1>`` / ``<h2>`` / ``<table>`` markup now uses
  ``Element("tag", ...)``.
- core.py: drop the ``Component()`` function and its back-compat note;
  ``common/components/__init__`` no longer exports it.
- Tests that exercised the shim now target ``Element`` directly
  (test_components cache/escaping/edge-case classes; test_node_tree drops the
  legacy-parity and legacy-bridge cases, which ``Element`` coverage subsumes).
- CLAUDE.md: drop the "legacy Component retained for back-compat" notes.

Full suite green (443; one obsolete legacy-bridge test removed).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

games/views/auth.py

@@ -3,16 +3,16 @@ registration/login.html)."""
 
 from django.contrib.auth import views as auth_views
 from django.http import HttpResponse
-from django.utils.safestring import SafeText, mark_safe
+from django.utils.safestring import mark_safe
 
-from common.components import Component, CsrfInput, Div, Input
+from common.components import CsrfInput, Div, Element, Input, Node
 from common.components.primitives import Td, Tr
 from common.layout import render_page
 
 
-def _login_content(form, request) -> SafeText:
-    table = Component(
-        tag_name="table",
+def _login_content(form, request) -> Node:
+    table = Element(
+        "table",
         children=[
             CsrfInput(request),
             mark_safe(str(form.as_table())),
@@ -31,13 +31,13 @@ def _login_content(form, request) -> SafeText:
     return Div(
         [("class", "flex items-center flex-col")],
         [
-            Component(
-                tag_name="h2",
+            Element(
+                "h2",
                 attributes=[("class", "text-3xl text-white mb-8")],
                 children=["Please log in to continue"],
             ),
-            Component(
-                tag_name="form",
+            Element(
+                "form",
                 attributes=[("method", "post")],
                 children=[table],
             ),