Fix the Segment region input and invite duplicates

The region is a two-value allow-list the server resolves to an API host,
but it rendered as a free-text field: only PostHog is special-cased in
the API-key dialog, everything else falls through to a generic Field.
Typing "EU1" — the region Segment's own UI shows for the EU workspace —
passed the non-empty check, then failed the mutation, and the dialog's
generic error blamed the API key. It is a select now, so the label no
longer has to spell the accepted values out.

An invite that has already been accepted can still be listed, and the
member and the invite were keyed differently (user ID vs email), so the
same person surfaced as two rows — one active with roles, one inactive
without. Invites for an email already seen among members are dropped.

Per-user permission errors now name the user, and the probe URL builds
its query with url.Values rather than a hand-written string.

The region-to-host mapping is the only API-key setting that derives a
value instead of storing input verbatim, and it had no test; a typo in
either host would only have surfaced as a live 404.

Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>

apps/console/src/pages/organizations/access-reviews/dialogs/_components/APIKeyConnectorDialog.tsx

@@ -26,6 +26,8 @@ import {
   DialogContent,
   DialogFooter,
   Field,
+  Option,
+  Select,
   useDialogRef,
   useToast,
 } from "@probo/ui";
@@ -248,7 +250,8 @@ export function APIKeyConnectorDialog({
   };
 
   // PostHog renders a dedicated deployment selector (Cloud region or
-  // self-hosted URL); every other provider falls back to generic fields.
+  // self-hosted URL) and Segment a region selector; every other provider falls
+  // back to generic fields.
   const renderAPIKeyExtraSettings = () => {
     if (!provider) {
       return null;
@@ -263,6 +266,25 @@ export function APIKeyConnectorDialog({
       );
     }
 
+    // The server maps this to a regional API host and rejects anything outside
+    // the allow-list, so it must not be typed by hand.
+    if (provider.provider === "SEGMENT") {
+      return (
+        <div className="space-y-1.5">
+          <label className="text-sm font-medium">{__("Region")}</label>
+          <Select
+            value={extraSettingValues.region ?? ""}
+            onValueChange={(val: string) =>
+              setExtraSettingValues(prev => ({ ...prev, region: val }))}
+            placeholder={__("Select a region")}
+          >
+            <Option value="US">{__("United States")}</Option>
+            <Option value="EU">{__("Europe")}</Option>
+          </Select>
+        </div>
+      );
+    }
+
     return provider.extraSettings.map((setting) => {
       const value = extraSettingValues[setting.key] ?? "";
       return (