feat: add date systems menu to calendar days

Right-clicking a calendar day now lists every configured date-prefixed note system. Journal notes are singletons; {title} formats support multiple notes per date, such as meetings.\n\nAdds default Journal and Meeting systems, configurable settings UI, safe filename/title handling, one shared dated-note creation path, and a compiled menu smoke test fixture in the test vault.

QA.md

@@ -70,6 +70,19 @@
 - [ ] Note indicator dots show on days with existing .md files
 - [ ] Today is highlighted with accent border
 
+
+## Calendar: Date systems
+
+- [ ] Right-click a date with a daily note, journal note, and meeting note → full-date header, then all three systems appear in the menu
+- [ ] Right-click a date with no date-system notes → each single-note system offers a create action and the many-note system offers “New …”
+- [ ] Right-click a date with one meeting → the existing meeting and “New meeting note…” both appear
+- [ ] Create a second meeting for the same date → it is created with that date prefix and both meetings appear on the next right-click
+- [ ] Ctrl/Cmd-click an existing date-system menu entry → it opens in a new tab
+- [ ] Submit an empty title for a new many-note system → a clear notice appears and no malformed file is created
+- [ ] Add a date system in Settings → Date systems → it appears in the day menu
+- [ ] Reorder and delete date systems → the day menu immediately follows the configured order and removes the deleted system
+- [ ] Enter a non-empty name format with no date token → Settings shows the inline warning
+- [ ] Left-click a day still opens/creates its daily note; middle-click still opens it in a new tab
 ## Recent Files (Regression)
 
 - [ ] Opening a file adds it to recent files