feat: add OAuth proxy support to eliminate CORS issues

Add server-side proxy endpoints for OAuth discovery, client registration,
and token exchange to avoid CORS issues when using proxy connection mode.

Server proxy endpoints:
- GET /oauth/resource-metadata - proxies OAuth protected resource metadata
- GET /oauth/metadata - proxies OAuth authorization server metadata
- POST /oauth/register - proxies dynamic client registration
- POST /oauth/token - proxies token exchange

Client changes:
- Construct correct RFC 9728/8414 path-aware well-known URLs client-side
- Route all OAuth discovery through proxy when in proxy connection mode
- Eliminate direct browser fetches that fail with CORS in proxy mode

client/src/components/AuthDebugger.tsx

@@ -7,12 +7,15 @@ import { OAuthFlowProgress } from "./OAuthFlowProgress";
 import { OAuthStateMachine } from "../lib/oauth-state-machine";
 import { SESSION_KEYS } from "../lib/constants";
 import { validateRedirectUrl } from "@/utils/urlValidation";
+import { InspectorConfig } from "../lib/configurationTypes";
 
 export interface AuthDebuggerProps {
   serverUrl: string;
   onBack: () => void;
   authState: AuthDebuggerState;
   updateAuthState: (updates: Partial<AuthDebuggerState>) => void;
+  connectionType: "direct" | "proxy";
+  config: InspectorConfig;
 }
 
 interface StatusMessageProps {
@@ -60,6 +63,8 @@ const AuthDebugger = ({
   onBack,
   authState,
   updateAuthState,
+  connectionType,
+  config,
 }: AuthDebuggerProps) => {
   // Check for existing tokens on mount
   useEffect(() => {
@@ -103,8 +108,9 @@ const AuthDebugger = ({
   }, [serverUrl, updateAuthState]);
 
   const stateMachine = useMemo(
-    () => new OAuthStateMachine(serverUrl, updateAuthState),
-    [serverUrl, updateAuthState],
+    () =>
+      new OAuthStateMachine(serverUrl, updateAuthState, connectionType, config),
+    [serverUrl, updateAuthState, connectionType, config],
   );
 
   const proceedToNextStep = useCallback(async () => {
@@ -150,11 +156,16 @@ const AuthDebugger = ({
         latestError: null,
       };
 
-      const oauthMachine = new OAuthStateMachine(serverUrl, (updates) => {
-        // Update our temporary state during the process
-        currentState = { ...currentState, ...updates };
-        // But don't call updateAuthState yet
-      });
+      const oauthMachine = new OAuthStateMachine(
+        serverUrl,
+        (updates) => {
+          // Update our temporary state during the process
+          currentState = { ...currentState, ...updates };
+          // But don't call updateAuthState yet
+        },
+        connectionType,
+        config,
+      );
 
       // Manually step through each stage of the OAuth flow
       while (currentState.oauthStep !== "complete") {