chore: upgrade Rails to 7.2.3.1 (#13437)

This upgrades Chatwoot to Rails 7.2.3.1 while retaining the current
Rails 7.0 framework defaults, so the runtime upgrade can be deployed and
observed independently from default-behavior changes.

## What changed

- Upgrade Rails and the compatible dependency set to Rails 7.2.3.1.
- Keep `config.load_defaults 7.0` for a staged, lower-risk rollout.
- Replace the unmaintained Azure Active Storage fork with the maintained
`azure-blob` adapter while preserving the `microsoft` service name.
- Pin Sidekiq 7.3.10 with `connection_pool` 2.x after validating
scheduled-job execution against Redis.
- Update Rails 7.2 compatibility surfaces in Active Record, strong
parameters, migrations, storage, and tests.
- Add read-only production preflight checks, an opt-in Active Storage
smoke script, a deployment runbook, and the full Rails 7.2/8.0/8.1
assessment.

## How to test

1. Sign in and verify the dashboard and conversation UI load normally.
2. Open the agent-management modal and confirm agent data is rendered.
3. Create an API inbox and wait for the asynchronous deletion flow to
complete.
4. Open Super Admin pages, including instance status and account-user
management.
5. Upload and download an attachment using the configured Active Storage
service.
6. Confirm recurring Sidekiq Cron jobs register and execute after
startup.

## Rollout

Follow `docs/rails_upgrades/7_2.md` for pre-deploy checks, deployment
order, smoke tests, monitoring, and rollback. Run `bundle exec rails
runner script/rails_upgrade/preflight.rb` against a
production-equivalent environment before rollout.

## Tracking

- [CW-5863 — Upgrade Rails to
8+](https://linear.app/chatwoot/issue/CW-5863/upgrade-rails-to-8)
- [Rails 7.2 to 8.1 upgrade and production rollout
plan](https://linear.app/chatwoot/document/chatwoot-rails-72-to-81-upgrade-and-production-rollout-plan-44e9f4964cb2)

---------

Co-authored-by: Shivam Mishra <scm.mymail@gmail.com>
Co-authored-by: Sony Mathew <2040199+sony-mathew@users.noreply.github.com>
Co-authored-by: Sony Mathew <sony@chatwoot.com>
Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>
Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

lib/seeders/reports/message_creator.rb

@@ -15,7 +15,7 @@ class Seeders::Reports::MessageCreator
   end
 
   def create_messages
-    message_count = rand(MESSAGES_PER_CONVERSATION..MESSAGES_PER_CONVERSATION + 5)
+    message_count = rand(MESSAGES_PER_CONVERSATION..(MESSAGES_PER_CONVERSATION + 5))
     first_agent_reply = true
 
     message_count.times do |i|