chore: remove IS_AI_ENABLED feature flag (#19916)

## Summary
- AI is now GA, so the public/lab `IS_AI_ENABLED` flag is removed from
`FeatureFlagKey`, the public flag catalog, and the dev seeder.
- Drops every backend `@RequireFeatureFlag(IS_AI_ENABLED)` guard (agent,
agent chat, chat subscription, role-to-agent assignment, workflow AI
step creation) and the now-unused `FeatureFlagModule`/`FeatureFlagGuard`
wiring in the AI and workflow modules.
- Removes frontend gating from settings nav, role
permissions/assignment/applicability, command menu hotkeys, side panel,
mobile/drawer nav, and the agent chat provider so AI UI is always on.
Tests and generated GraphQL/SDK schemas updated accordingly.

## Test plan
- [x] `npx nx typecheck twenty-shared`
- [x] `npx nx typecheck twenty-server`
- [x] `npx nx typecheck twenty-front`
- [x] `npx nx lint:diff-with-main twenty-server`
- [x] `npx nx lint:diff-with-main twenty-front`
- [x] `npx jest --config=packages/twenty-server/jest.config.mjs
feature-flag`
- [x] `npx jest --config=packages/twenty-server/jest.config.mjs
workspace-entity-manager`
- [ ] Manual smoke test: AI features still accessible without any flag
row in `featureFlag`

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

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

packages/twenty-front/src/modules/ai/components/AgentChatProvider.tsx

@@ -1,17 +1,9 @@
 import { AgentChatProviderContent } from '@/ai/components/AgentChatProviderContent';
-import { useIsFeatureEnabled } from '@/workspace/hooks/useIsFeatureEnabled';
-import { FeatureFlagKey } from '~/generated-metadata/graphql';
 
 export const AgentChatProvider = ({
   children,
 }: {
   children: React.ReactNode;
 }) => {
-  const isAiEnabled = useIsFeatureEnabled(FeatureFlagKey.IS_AI_ENABLED);
-
-  return (
-    <AgentChatProviderContent isAiEnabled={isAiEnabled}>
-      {children}
-    </AgentChatProviderContent>
-  );
+  return <AgentChatProviderContent>{children}</AgentChatProviderContent>;
 };

packages/twenty-front/src/modules/ai/components/AgentChatProviderContent.tsx

@@ -10,26 +10,20 @@ import { Suspense } from 'react';
 
 export const AgentChatProviderContent = ({
   children,
-  isAiEnabled,
 }: {
   children: React.ReactNode;
-  isAiEnabled: boolean;
 }) => {
   return (
     <Suspense fallback={null}>
       <AgentChatComponentInstanceContext.Provider
         value={{ instanceId: 'agentChatComponentInstance' }}
       >
-        {isAiEnabled && (
-          <>
-            <AgentChatThreadInitializationEffect />
-            <AgentChatMessagesFetchEffect />
-            <AgentChatStreamSubscriptionEffect />
-            <AgentChatStreamingPartsDiffSyncEffect />
-            <AgentChatSessionStartTimeEffect />
-            <AgentChatStreamingAutoScrollEffect />
-          </>
-        )}
+        <AgentChatThreadInitializationEffect />
+        <AgentChatMessagesFetchEffect />
+        <AgentChatStreamSubscriptionEffect />
+        <AgentChatStreamingPartsDiffSyncEffect />
+        <AgentChatSessionStartTimeEffect />
+        <AgentChatStreamingAutoScrollEffect />
         {children}
       </AgentChatComponentInstanceContext.Provider>
     </Suspense>