feat: admin editable email templates

addresses #869eg7ptr

config/services.yaml

@@ -9,6 +9,13 @@ parameters:
 
     teamer_inactive_period: '-2 years'
 
+    # Deadlines quoted to teamers in the transactional mails. They are passed to the mail
+    # texts as placeholders rather than typed into the wording, so what an admin edits can
+    # never drift from the period the application actually works with.
+    contract_upload_deadline_days: 7
+    # Also drives when the reminder goes out: three days before the deadline expires.
+    invoice_upload_deadline_days: 14
+
     # Messenger transport the mails of a teamer mailing are queued on. An X-Bus-Transport
     # header wins over the routing in messenger.yaml (see SendersLocator::getSenders),
     # so this is what keeps a mailing off the shared queue - and what has to be switched
@@ -58,6 +65,11 @@ services:
             $xmlExport: '@xml_export.storage'
             $xmlDump: '@xml_dump.storage'
             $teamerInactivePeriod: '%teamer_inactive_period%'
+            $contractUploadDeadlineDays: '%contract_upload_deadline_days%'
+            $invoiceUploadDeadlineDays: '%invoice_upload_deadline_days%'
+            # Only the path enters the container - the file itself is parsed on demand by
+            # App\Config\EmailTextCatalog, since its contents matter on few requests.
+            $emailTextsFile: '%kernel.project_dir%/config/email_texts.yaml'
             $mailingBusTransport: '%mailing_bus_transport%'
 
     App\: