feat: add developer-mode startup and stack hydration timing (#1619)

* feat: add developer-mode startup and stack hydration timing

Instrument boot-to-list and detail hydration with commit-aligned milestones, truthful request stages, and destination/gateway debug duration logs so performance work is guided by measurements.

* fix: redact stack names and complete hydration request stages

Stop logging stack identifiers in containers debug timing, and record state_dispatch (plus detail fetch spans) so copied reports match the advertised stage breakdown.

frontend/src/context/AuthContext.tsx

@@ -1,4 +1,5 @@
 import { createContext, useContext, useState, useEffect, useCallback, type ReactNode } from 'react';
+import { markMilestone } from '@/lib/hydrationTiming';
 
 type AppStatus = 'loading' | 'needsSetup' | 'notAuthenticated' | 'mfaChallenge' | 'authenticated';
 
@@ -109,6 +110,13 @@ export function AuthProvider({ children }: { children: ReactNode }) {
     }
   };
 
+  // One-shot boot milestone: the auth gate has resolved to a terminal status
+  // (setup, login, MFA, or authenticated), so the app can leave the splash.
+  useEffect(() => {
+    if (appStatus === 'loading') return;
+    markMilestone('auth_resolved');
+  }, [appStatus]);
+
   useEffect(() => {
     checkAuth();
     const handleUnauthorized = () => {