Remove dangling :maybe_redirect_com callbacks (fixes 500s)

The rebrand commit (2796ddf4) deleted the `maybe_redirect_com` helper
from ApplicationController — it was a DocuSeal-specific `.co → .com`
301 redirect with no role in WaboSign — but missed four
`prepend_before_action :maybe_redirect_com` / `before_action` callsites
that referenced it. Rails resolves before_action symbols at request
time via `send`, so every gated action raised NoMethodError → HTTP 500.

Affected URLs (now fixed):
  - GET /settings/esign                          (admin)
  - GET /submissions/:id                         (admin)
  - GET /start_form/:slug + /completed           (public — signers)
  - GET /submissions/preview/:slug + /completed  (public)

No replacement needed — the original redirect was DocuSeal-specific.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/controllers/esign_settings_controller.rb

@@ -11,8 +11,6 @@ class EsignSettingsController < ApplicationController
     end
   end
 
-  prepend_before_action :maybe_redirect_com, only: %i[show]
-
   before_action :load_encrypted_config
   authorize_resource :encrypted_config, parent: false, only: %i[new create]
   authorize_resource :encrypted_config, only: %i[update destroy show]

app/controllers/start_form_controller.rb

@@ -7,7 +7,6 @@ class StartFormController < ApplicationController
   skip_authorization_check
 
   around_action :with_browser_locale, only: %i[show update completed]
-  before_action :maybe_redirect_com, only: %i[show completed]
   before_action :load_resubmit_submitter, only: :update
   before_action :load_template
   before_action :authorize_start!, only: :update

app/controllers/submissions_controller.rb

@@ -6,8 +6,6 @@ class SubmissionsController < ApplicationController
 
   load_and_authorize_resource :submission, only: %i[show destroy]
 
-  prepend_before_action :maybe_redirect_com, only: %i[show]
-
   before_action only: :create do
     authorize!(:create, Submission)
   end

app/controllers/submissions_preview_controller.rb

@@ -5,8 +5,6 @@ class SubmissionsPreviewController < ApplicationController
   skip_before_action :authenticate_user!
   skip_authorization_check
 
-  prepend_before_action :maybe_redirect_com, only: %i[show completed]
-
   TTL = 40.minutes
 
   def show