fix(meta): add independent incident runtime controls (#15318)

This restores the temporary Meta incident safeguards with two
independent runtime controls for Chatwoot Cloud. Super admins can now
re-enable Instagram messaging first and keep new Meta inbox creation
disabled until onboarding is stable.

When messaging is disabled, Instagram conversations show the incident
notice and remain in private-note mode. The separate inbox-creation
control disables Facebook, Instagram, and WhatsApp Embedded Signup entry
points. Self-hosted installations remain unchanged.

Related: https://github.com/chatwoot/chatwoot/pull/15210
Related: https://status.chatwoot.com/incident/976975

### Things to know

- `DISABLE_META_MESSAGE_SENDING` affects Instagram messaging only.
- `DISABLE_META_INBOX_CREATION` affects Facebook, Instagram, and
WhatsApp Embedded Signup inbox creation.
- Both controls default to `true` for the active incident and are
editable from Super Admin installation configs.
- The Cloud-only boundary is enforced by the dashboard configuration
getters.

### How to test

1. Open Super Admin → Installation Configs and set
`DISABLE_META_MESSAGE_SENDING` to `false`.
2. Reload an Instagram conversation and confirm the incident banner
disappears and the runtime restriction no longer forces private-note
mode.
3. Set the flag back to `true`, reload, and confirm the banner and
restriction return.
4. Set `DISABLE_META_INBOX_CREATION` to `false`, reload the Facebook,
Instagram, or WhatsApp Embedded Signup setup flow, and confirm
connection is enabled.
5. Set the flag back to `true`, reload, and confirm the incident notice
appears and connection is disabled.

---------

Co-authored-by: Muhsin <12408980+muhsin-k@users.noreply.github.com>

config/installation_config.yml

@@ -237,6 +237,18 @@
 # ------- End of Context.dev Config ------- #
 
 # ------- Chatwoot Internal Config for Cloud ----#
+- name: DISABLE_META_INBOX_CREATION
+  value: true
+  display_title: 'Disable Meta Inbox Creation'
+  description: 'Disable Facebook, Instagram, and WhatsApp Embedded Signup inbox creation on Chatwoot Cloud during Meta incidents'
+  locked: false
+  type: boolean
+- name: DISABLE_META_MESSAGE_SENDING
+  value: true
+  display_title: 'Disable Meta Message Sending'
+  description: 'Disable Instagram message sending on Chatwoot Cloud during Meta incidents'
+  locked: false
+  type: boolean
 - name: CHATWOOT_INBOX_TOKEN
   value:
   display_title: 'Inbox Token'