Translate the rule sentences into Dutch

#261 rebuilt the Sieve rule summaries and the recurrence descriptions as whole
sentences with placeholders, so that a translator can move the parts rather
than being handed " and " on its own. This is the Dutch half of that.

32 strings and 9 plural forms. The ordinals are words -- there is no suffix to
append here, which was the point -- and the day and item lists are joined by
Intl.ListFormat rather than a translated separator.

web/src/locales/nl.ts

@@ -1251,8 +1251,54 @@ export const catalog: Catalog = {
     "This message was sent automatically, so no read receipt is offered.": "Dit bericht is automatisch verzonden, dus er wordt geen leesbevestiging aangeboden.",
     "This server will not hold a message longer than {span}.": "Deze server houdt een bericht niet langer dan {span} vast.",
     "Upload failed": "Uploaden mislukt",
+    // ── Third pass ──────────────────────────────────────────────────────
+    // Sentences that lib/ and store/ were building in English, and the two
+    // swipe labels that reach t() through a variable and so were invisible
+    // to a scan for t("literal"). See #259.
+    "Every {n} {frequency}": "Elke {n} {frequency}",
+    "Monthly": "Maandelijks",
+    "Monthly on day {days}": "Maandelijks op dag {days}",
+    "Monthly on the {ordinal} {weekday}": "Maandelijks op de {ordinal} {weekday}",
+    "Monthly on {weekday}": "Maandelijks op {weekday}",
+    "Weekly": "Wekelijks",
+    "Weekly on {days}": "Wekelijks op {days}",
+    "add {flag}": "{flag} toevoegen",
+    "always": "altijd",
+    "body contains \"{value}\"": "tekst bevat \"{value}\"",
+    "body does not contain \"{value}\"": "tekst bevat niet \"{value}\"",
+    "delete it": "verwijderen",
+    "fifth": "vijfde",
+    "first": "eerste",
+    "forward to {address}": "doorsturen naar {address}",
+    "fourth": "vierde",
+    "keep it": "behouden",
+    "last": "laatste",
+    "mark it read": "als gelezen markeren",
+    "move to {folder}": "verplaatsen naar {folder}",
+    "reject it": "weigeren",
+    "remove {flag}": "{flag} verwijderen",
+    "second": "tweede",
+    "size is over {n} KB": "grootte boven {n} KB",
+    "size is under {n} KB": "grootte onder {n} KB",
+    "star it": "een ster geven",
+    "stop": "stoppen",
+    "third": "derde",
+    "{header} address {op} \"{value}\"": "{header}-adres {op} \"{value}\"",
+    "{header} {op} \"{value}\"": "{header} {op} \"{value}\"",
+    "{rule}, until {date}": "{rule}, tot {date}",
+    "{tests} → {actions}": "{tests} → {actions}",
   },
   plurals: {
+    // ── Third pass ─────────────────────────────────────────────────────
+    "Every {n} days": { one: "Elke dag", other: "Elke {n} dagen" },
+    "Every {n} months": { one: "Elke maand", other: "Elke {n} maanden" },
+    "Every {n} months on day {days}": { one: "Elke maand op dag {days}", other: "Elke {n} maanden op dag {days}" },
+    "Every {n} months on the {ordinal} {weekday}": { one: "Elke maand op de {ordinal} {weekday}", other: "Elke {n} maanden op de {ordinal} {weekday}" },
+    "Every {n} months on {weekday}": { one: "Elke maand op {weekday}", other: "Elke {n} maanden op {weekday}" },
+    "Every {n} weeks": { one: "Elke week", other: "Elke {n} weken" },
+    "Every {n} weeks on {days}": { one: "Elke week op {days}", other: "Elke {n} weken op {days}" },
+    "Every {n} years": { one: "Elk jaar", other: "Elke {n} jaar" },
+    "{rule}, {n} times": { one: "{rule}, {n} keer", other: "{rule}, {n} keer" },
     // ── Third pass ─────────────────────────────────────────────────────
     "Move {n} messages to Trash?": { one: "{n} bericht naar de Prullenbak verplaatsen?", other: "{n} berichten naar de Prullenbak verplaatsen?" },
     "{n} days": { one: "{n} dag", other: "{n} dagen" },