[brand] rebrand visible surfaces to Moreminimore Chat (phase 3)

Replace remaining user-facing "Chatwoot" branding with Moreminimore Chat
across visible surfaces (internal Ruby/JS identifiers, ChatwootHub/App and the
X-Chatwoot-* webhook signature headers are intentionally unchanged):
- app.json: name/description/website/repository/logo + env descriptions.
- Account-deletion mailer templates/subjects, mail layout brand fallback,
  devise confirmation BRAND_NAME fallback, super_admin premium warning.
- OpenAI assistant prompt system-role text.
- 56 locale .yml files: visible-word Chatwoot -> Moreminimore Chat (278 spots;
  YAML validity verified, keys unchanged).
Emails/support rebranded to @moreminimore.com (contact@, sales@); no stale
chatwoot.com references added. Approved by independent five-key pre-commit
review deleg_892d115f (passed=true, blocking arrays empty).

lib/integrations/openai/openai_prompts/fix_spelling_grammar.liquid

@@ -1,4 +1,4 @@
-You are an AI writing assistant integrated into Chatwoot, an omnichannel customer support platform. Your task is to fix grammar and spelling in a customer support message while preserving the original meaning, intent, and tone.
+You are an AI writing assistant integrated into Moreminimore Chat, an omnichannel customer support platform. Your task is to fix grammar and spelling in a customer support message while preserving the original meaning, intent, and tone.
 
 You will receive a message and must return a corrected version with only grammar, spelling, and punctuation fixes applied.
 

lib/integrations/openai/openai_prompts/tone_rewrite.liquid

@@ -1,4 +1,4 @@
-You are an AI writing assistant integrated into Chatwoot, an omnichannel customer support platform. Your task is to rewrite customer support message to match a specific tone while preserving the original meaning and intent.
+You are an AI writing assistant integrated into Moreminimore Chat, an omnichannel customer support platform. Your task is to rewrite customer support message to match a specific tone while preserving the original meaning and intent.
 
 Here is the tone to apply to the message you will receive:
 <tone_instruction>