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/side-panel/components/SidePanelTopBarRightCornerIcon.tsx

@@ -4,14 +4,12 @@ import { sidePanelPageState } from '@/side-panel/states/sidePanelPageState';
 import { sidePanelSearchObjectFilterState } from '@/side-panel/states/sidePanelSearchObjectFilterState';
 import { useAtomState } from '@/ui/utilities/state/jotai/hooks/useAtomState';
 import { useAtomStateValue } from '@/ui/utilities/state/jotai/hooks/useAtomStateValue';
-import { useIsFeatureEnabled } from '@/workspace/hooks/useIsFeatureEnabled';
 import { styled } from '@linaria/react';
 import { t } from '@lingui/core/macro';
 import { SidePanelPages } from 'twenty-shared/types';
 import { IconEdit } from 'twenty-ui/display';
 import { IconButton } from 'twenty-ui/input';
 import { useIsMobile } from 'twenty-ui/utilities';
-import { FeatureFlagKey } from '~/generated-metadata/graphql';
 import { themeCssVariables } from 'twenty-ui/theme-constants';
 
 const StyledIconButtonContainer = styled.div`
@@ -20,7 +18,6 @@ const StyledIconButtonContainer = styled.div`
 
 export const SidePanelTopBarRightCornerIcon = () => {
   const isMobile = useIsMobile();
-  const isAiEnabled = useIsFeatureEnabled(FeatureFlagKey.IS_AI_ENABLED);
   const sidePanelPage = useAtomStateValue(sidePanelPageState);
   const { switchToNewChat } = useSwitchToNewAiChat();
   const [sidePanelSearchObjectFilter, setSidePanelSearchObjectFilter] =
@@ -42,7 +39,7 @@ export const SidePanelTopBarRightCornerIcon = () => {
     SidePanelPages.ViewPreviousAiChats,
   ].includes(sidePanelPage);
 
-  if (isMobile || !isAiEnabled || !isOnAskAiPage) {
+  if (isMobile || !isOnAskAiPage) {
     return null;
   }