revert(frontend): keep provider clone URL as ?id= (revert part of 04702c3)

Reverts the O10 part of commit 04702c3. The original change renamed
the provider clone URL parameter from `?id=` to `?clone=`. On second
look the rename solved no real problem:

- No security issue: PentAGI is a single-tenant local admin tool, so
  there is no cross-tenant info leak from a shared URL.
- No bug: the form behaviour was identical before and after.
- No UX impact: the URL is generated by the "Clone" action, not typed
  by users; the bare `?id=` is also explicit enough in context
  (settings-provider.tsx gates it on `isNew`, so the meaning is
  "source provider to clone from").

What the rename did cost: it broke backward compatibility with any
bookmarks/links saved in `?id=` form. Restore `?id=` to remove the
needless churn.

The rest of commit 04702c3 (O7 dialog case, O8 "API Tokens" unify,
O11 button label + JSDoc, O12 italic placeholder) addressed real
inconsistencies and stays in place.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/pages/settings/settings-provider.tsx

@@ -877,7 +877,7 @@ function SettingsProvider() {
 
     const formQueryParams = useMemo(
         () => ({
-            clone: searchParams.get('clone'),
+            id: searchParams.get('id'),
             type: searchParams.get('type'),
         }),
         [searchParams],
@@ -1001,7 +1001,7 @@ function SettingsProvider() {
 
         if (isNew || !providerId) {
             const queryType = formQueryParams.type ?? undefined;
-            const queryId = formQueryParams.clone;
+            const queryId = formQueryParams.id;
 
             if (queryId && data?.settingsProviders?.userDefined) {
                 const sourceProvider = data.settingsProviders.userDefined.find((p: Provider) => p.id == queryId);

frontend/src/pages/settings/settings-providers.tsx

@@ -103,7 +103,7 @@ function SettingsProviders() {
 
     const handleProviderClone = useCallback(
         (providerId: string) => {
-            navigate(`/settings/providers/new?clone=${providerId}`);
+            navigate(`/settings/providers/new?id=${providerId}`);
         },
         [navigate],
     );