Fix A() component

Replaced single `url` parameter with explicit `url_name` (URL pattern name resolved via `reverse()`) and `href` (literal path). Fixes:
- Silent fallback (typos like `"ad_puchase"` silently became broken links) → now raises `NoReverseMatch` at render time
- `type(url) is str` gate → removed (implicit dual-mode eliminated entirely)
- Callable parameter (`url: Callable`) dead code → removed
- Implicit dual-mode (`url="name"` vs `url=reverse("name")`) → `url_name` vs `href` are now mutually exclusive params
- Inconsistent type annotation mixing `Callable` with string default → cleaned up
- Added `ValueError` when both `url_name` and `href` are provided
- Updated all 10 call sites across 6 view files and internal callers (`LinkedPurchase()`, `NameWithIcon()`)

tests/test_components.py

@@ -376,9 +376,24 @@ class ComponentReturnTypeTest(unittest.TestCase):
         self.assertIsInstance(result, SafeText)
 
     def test_a_literal_href(self):
-        result = components.A([], "x", url="/literal/path")
+        result = components.A([], "x", href="/literal/path")
         self.assertIn('href="/literal/path"', result)
 
+    def test_a_url_name_reversed(self):
+        from unittest.mock import patch
+        with patch("common.components.reverse", return_value="/resolved/url"):
+            result = components.A([], "link", url_name="some_name")
+            self.assertIn('href="/resolved/url"', result)
+
+    def test_a_no_url_or_href(self):
+        result = components.A([], "link")
+        self.assertIn('<a>link</a>', result)
+        self.assertNotIn('href=', result)
+
+    def test_a_both_url_name_and_href_raises(self):
+        with self.assertRaises(ValueError):
+            components.A(href="/path", url_name="some_name")
+
     def test_button_returns_safe_text(self):
         result = components.Button([], "click")
         self.assertIsInstance(result, SafeText)