fix: extract the param row constant and cover the manager bridge (#2018)

Copilot round 3 (both findings suppressed; both valid).

- The a11y fix in the previous commit added `align="flex-start"` to the row's
  `Group`, giving it two static layout props and so tripping the .withProps()
  rule in AGENTS.md — which applies to a single-use element too. Extracted as
  `AuthorizationParamRow`. (The sibling `KeyValueRows` Group carries one static
  prop and stays inline, correctly.)

- Added OAuthManager coverage for the config→provider bridge. The point is
  sharp: the provider test proves the merge and the runner test proves the
  options object, but nothing crossed the seam in `createOAuthProvider`, so
  deleting the `authorizationParams:` line left the feature dead with every
  test green. Verified by doing exactly that — both new cases now fail with
  `expected null to be 'corp-idp'` — then restoring it. The second case also
  pins the reserved-key drop through the manager path.

Signed-off-by: cliffhall <cliff@futurescale.com>

clients/web/src/components/groups/ServerSettingsForm/ServerSettingsForm.tsx

@@ -202,6 +202,13 @@ const FieldDescription = Text.withProps({
   c: "dimmed",
 });
 
+// `align="flex-start"` keeps the key/value/remove controls top-aligned when the
+// key input grows an error message, so the row doesn't jump as it appears.
+const AuthorizationParamRow = Group.withProps({
+  grow: true,
+  align: "flex-start",
+});
+
 const ClearStoredOAuthButton = Button.withProps({
   variant: "light",
   color: "red",
@@ -288,7 +295,7 @@ function AuthorizationParamRows({
       {params.map((param, index) => {
         const rowLabel = param.key.trim() || `row ${index + 1}`;
         return (
-          <Group key={index} grow align="flex-start">
+          <AuthorizationParamRow key={index}>
             <ClearableTextInput
               aria-label={`Authorization parameter name, ${rowLabel}`}
               placeholder="Parameter (e.g. kc_idp_hint)"
@@ -324,7 +331,7 @@ function AuthorizationParamRows({
             >
               X
             </RemoveIcon>
-          </Group>
+          </AuthorizationParamRow>
         );
       })}
     </>