chore: make all the deprecated feature flag reclaimable (#13646)

## Docs

https://www.notion.so/chatwoot/Redeeming-a-depreciated-feature-flag-313a5f274c9280f381cdd811eab42019?source=copy_link

## Description
Marks 8 unused feature flags as deprecated: true in features.yml,
freeing their bit slots for future reuse.
Removes dead code references from JS constants, help URLs, and
enterprise billing config.

## Type of change

- [ ] Bug fix (non-breaking change which fixes an issue)

## How Has This Been Tested?

- Simulated the "claim a slot" workflow 

## Checklist:

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [ ] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules

app/javascript/dashboard/featureFlags.js

@@ -21,10 +21,8 @@ export const FEATURE_FLAGS = {
   AUDIT_LOGS: 'audit_logs',
   INBOX_VIEW: 'inbox_view',
   SLA: 'sla',
-  RESPONSE_BOT: 'response_bot',
   CHANNEL_EMAIL: 'channel_email',
   CHANNEL_FACEBOOK: 'channel_facebook',
-  CHANNEL_TWITTER: 'channel_twitter',
   CHANNEL_WEBSITE: 'channel_website',
   CUSTOM_REPLY_DOMAIN: 'custom_reply_domain',
   CUSTOM_REPLY_EMAIL: 'custom_reply_email',
@@ -36,7 +34,6 @@ export const FEATURE_FLAGS = {
   CAPTAIN: 'captain_integration',
   CUSTOM_ROLES: 'custom_roles',
   CHATWOOT_V4: 'chatwoot_v4',
-  REPORT_V4: 'report_v4',
   CHANNEL_INSTAGRAM: 'channel_instagram',
   CHANNEL_TIKTOK: 'channel_tiktok',
   CONTACT_CHATWOOT_SUPPORT_TEAM: 'contact_chatwoot_support_team',

app/javascript/dashboard/helper/featureHelper.js

@@ -13,7 +13,6 @@ const FEATURE_HELP_URLS = {
   integrations: 'https://chwt.app/hc/integrations',
   labels: 'https://chwt.app/hc/labels',
   macros: 'https://chwt.app/hc/macros',
-  message_reply_to: 'https://chwt.app/hc/reply-to',
   reports: 'https://chwt.app/hc/reports',
   sla: 'https://chwt.app/hc/sla',
   team_management: 'https://chwt.app/hc/teams',