feat: Introduce the crm_v2 feature flag for CRM changes (#12014)

Introduce crm_v2 feature flag for our upcoming optimisations for CRM

---------

Co-authored-by: Sojan Jose <sojan@pepalo.com>

db/migrate/20250722152516_add_index_on_contact_type_and_account_id_to_contacts.rb

@@ -0,0 +1,7 @@
+class AddIndexOnContactTypeAndAccountIdToContacts < ActiveRecord::Migration[7.1]
+  disable_ddl_transaction!
+
+  def change
+    add_index :contacts, [:account_id, :contact_type], name: 'index_contacts_on_account_id_and_contact_type', algorithm: :concurrently
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.1].define(version: 2025_07_14_104358) do
+ActiveRecord::Schema[7.1].define(version: 2025_07_22_152516) do
   # These extensions should be enabled to support this database
   enable_extension "pg_stat_statements"
   enable_extension "pg_trgm"
@@ -539,6 +539,7 @@ ActiveRecord::Schema[7.1].define(version: 2025_07_14_104358) do
     t.string "country_code", default: ""
     t.boolean "blocked", default: false, null: false
     t.index "lower((email)::text), account_id", name: "index_contacts_on_lower_email_account_id"
+    t.index ["account_id", "contact_type"], name: "index_contacts_on_account_id_and_contact_type"
     t.index ["account_id", "email", "phone_number", "identifier"], name: "index_contacts_on_nonempty_fields", where: "(((email)::text <> ''::text) OR ((phone_number)::text <> ''::text) OR ((identifier)::text <> ''::text))"
     t.index ["account_id", "last_activity_at"], name: "index_contacts_on_account_id_and_last_activity_at", order: { last_activity_at: "DESC NULLS LAST" }
     t.index ["account_id"], name: "index_contacts_on_account_id"