Merge branch 'dev' into feature/read-only-store

dev gained the editable mail templates, which live in the store like everything
else -- so they follow the same read-only rules: the options dialog skips saving
them, save_mail_template() reports the store instead of a raw PermissionError,
and a store that cannot keep its own copy simply renders from the shipped
default.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/ccma/ui/member_tab.py

@@ -38,6 +38,7 @@ from ccma.ui.labels import display_label, storage_key
 from ccma.ui.messages import MessageAction, MessageBannerList, TabMessage
 from ccma.ui.payment_dialog import PaymentCreateDialog, PaymentEditDialog
 from ccma.ui.scrolling import ScrollableFrame
+from ccma.ui.welcome_mail_dialog import WelcomeMailDialog
 
 # Shared column sizing for the ledger-style tables (Forderungen/Zahlungen/Spenden): date-
 # and amount-like columns get the same fixed width, status columns get a third more
@@ -355,6 +356,13 @@ class MemberTab(ttk.Frame):
         self.claims.grid(row=1, column=0, sticky="nsew")
         self.claims.bind("<Double-1>", lambda _event: self._open_selected_claim())
         self.claims.bind("<Return>", lambda _event: self._open_selected_claim())
+        claim_actions = ttk.Frame(contribution_tab)
+        claim_actions.grid(row=2, column=0, sticky="e", pady=(8, 0))
+        ttk.Button(
+            claim_actions,
+            text="Willkommens- und Erstrechnungsmail",
+            command=self._send_welcome_mail,
+        ).pack(side="left")
 
         contribution_override_tab.columnconfigure(0, weight=1)
         contribution_override_tab.rowconfigure(1, weight=1)
@@ -1185,6 +1193,14 @@ class MemberTab(ttk.Frame):
         except OSError as exc:
             messagebox.showerror("Datei konnte nicht geöffnet werden", str(exc), parent=self)
 
+    def _send_welcome_mail(self) -> None:
+        WelcomeMailDialog(self, self.repository, self.member_id, self._welcome_mail_sent)
+
+    def _welcome_mail_sent(self) -> None:
+        self._refresh_documents()
+        self._refresh_events()
+        self.on_changed()
+
     def _create_document(self) -> None:
         DocumentTemplateDialog(
             self,