feat: add OpenDocument PDF templates

README.md

@@ -9,6 +9,8 @@ directory containing `member.json`, `contributions.json`, an append-only
 ## Development
 
 Requires Python 3.11+ with Tk support.
+PDF generation from document templates additionally requires LibreOffice or
+OpenOffice with a `soffice` command available on the system.
 
 ```bash
 python -m venv .venv
@@ -46,6 +48,10 @@ member-store/
 ├── repository.json
 ├── housekeeper.json
 ├── rules/
+├── templates/
+│   ├── Forderung.fodt
+│   ├── Mahnung.fodt
+│   └── Mitglied.fodt
 └── members/
     └── <uuid>/
         ├── member.json
@@ -54,6 +60,33 @@ member-store/
         └── files/
 ```
 
+## Document templates
+
+CCMA reads OpenDocument templates (`.fodt`, `.odt`, or `.ott`) from the
+store's `templates/` directory. The three initial `.fodt` files are editable
+with LibreOffice/OpenOffice and are copied only when their filename does not
+already exist. PDF files are generated locally and stored below the member's
+`files/documents/` directory. No office document content is sent to an
+external service.
+
+Placeholders use `{{group.field}}`. Available values include:
+
+- Member: `member.number`, `member.first_name`, `member.last_name`,
+  `member.full_name`, `member.email`, `member.birth_date`, `member.status`,
+  `member.accepted_at`, `member.started_at`
+- Claim: `claim.id`, `claim.title`, `claim.due_date`, `claim.total`,
+  `claim.paid`, `claim.balance`, `claim.status`, `claim.items`
+- Reminder: `reminder.id`, `reminder.level`, `reminder.name`,
+  `reminder.status`, `reminder.created_at`, `reminder.sent_at`,
+  `reminder.payment_deadline`, `reminder.payment_deadline_days`,
+  `reminder.fee`, `reminder.detail`, `reminder.channel`
+- Document: `document.date`, `document.datetime`
+
+Claim placeholders are available from a claim tab. Reminder placeholders are
+available when a reminder row is selected before opening the document dialog.
+Unknown or unavailable placeholders stop generation with a clear error rather
+than producing an incomplete letter.
+
 ## Housekeeper rules
 
 The housekeeper runs every rule for every member. Built-in Python rules live in