Second extraction pass: the strings the codemod could not see

`i18n:coverage` reported 100% while a hundred-odd strings rendered
English in every language. It was not wrong about what it measured: it
reads JSX text, and none of these were JSX text. They were toast
arguments, `confirmDialog({ title, confirmLabel })` props, `title=` and
`aria-label=` attributes, and template literals — every one built from an
expression the codemod cannot read.

176 source strings and 15 plural sets now go through t() and plural(),
translated into all nine languages. Where English put a word in a slot,
the sentence is spelled out per branch instead: `Filter ${verb}` became
"Filter saved" and "Filter created", because which word agrees with what,
and where it sits, is not a property English gets to decide for everyone.
Counts that were `${n} message${n === 1 ? "" : "s"}` are plural() calls,
so Russian and Ukrainian get three forms and Japanese and Chinese get the
one they actually have.

Two of the catalogue's own conventions were worth learning the hard way.
Plural entries are keyed on the English *other* form, not `one` — `one`
is a form English happens to have and Japanese does not. And a constant
table holding English that is translated at the render site is fine: the
literal is a key, not a leak.

Which is what the new check encodes. `scripts/i18n-literals.mjs` accepts
a string that is wrapped where it is written or is a catalogue key
somewhere, and refuses one that is neither — a string no catalogue can
translate, however many languages ship. It found twenty more than my own
sweep had, including the stale-folder toast seen in production. It runs
as part of `npm run i18n:check`.

Also fixed: the catalogue is now awaited before the first paint. The
tree is rebuilt when a catalogue lands, so components recover on their
own, but a string computed in an effect does not — a toast fired in that
gap is emitted in English and stays English. The wait costs nothing
visible, since the session bootstrap already shows a spinner and English
resolves immediately.

And the Japanese agenda title loses a space Japanese does not use:
"{date} からの予定" was written with the English habit of spacing around
a placeholder.

web/src/views/settings/IdentitiesSettings.tsx

@@ -48,13 +48,13 @@ export function IdentitiesSettings() {
             <button
               className="btn btn-sm btn-ghost"
               disabled={isAlwaysVisible(i.id, [defaultId])}
-              title={isAlwaysVisible(i.id, [defaultId]) ? "The default identity is always offered when composing" : hidden.includes(i.id) ? "Show this in the compose picker" : "Hide this from the compose picker"}
+              title={isAlwaysVisible(i.id, [defaultId]) ? t("The default identity is always offered when composing") : hidden.includes(i.id) ? t("Show this in the compose picker") : t("Hide this from the compose picker")}
               onClick={(e) => { e.stopPropagation(); toggleHidden(i.id); }}
             >
               {hidden.includes(i.id) ? <><Eye size={14} /> {t("Show when composing")}</> : <><EyeOff size={14} /> {t("Hide when composing")}</>}
             </button>
             {i.mayDelete && (
-              <button className="icon-btn sm danger" aria-label={t("Delete identity")} onClick={async (e) => { e.stopPropagation(); if (await confirmDialog({ title: "Delete this identity?", confirmLabel: "Delete", danger: true })) { try { await useMail.getState().destroyIdentity(i.id); } catch (err) { toast.error((err as Error).message); } } }}><Trash2 size={16} /></button>
+              <button className="icon-btn sm danger" aria-label={t("Delete identity")} onClick={async (e) => { e.stopPropagation(); if (await confirmDialog({ title: t("Delete this identity?"), confirmLabel: t("Delete"), danger: true })) { try { await useMail.getState().destroyIdentity(i.id); } catch (err) { toast.error((err as Error).message); } } }}><Trash2 size={16} /></button>
             )}
           </div>
           {hidden.includes(i.id) && <div className="hint" style={{ marginTop: 4 }}>{t("Not offered when composing. It still receives mail, and you can still send from it by showing it again.")}</div>}
@@ -105,7 +105,7 @@ function IdentityDialog({ identity, onClose }: { identity: Partial<Identity>; on
       };
       if (!identity.id) patch.email = email.trim();
       await useMail.getState().saveIdentity(identity.id ?? null, patch);
-      toast.success("Identity saved");
+      toast.success(t("Identity saved"));
       onClose();
     } catch (err) {
       toast.error((err as Error).message);
@@ -114,7 +114,7 @@ function IdentityDialog({ identity, onClose }: { identity: Partial<Identity>; on
     }
   };
   return (
-    <Dialog open onClose={onClose} title={identity.id ? "Edit identity" : "New identity"} size="lg" footer={<><button className="btn" onClick={onClose}>{t("Cancel")}</button><button className="btn btn-primary" disabled={busy} onClick={() => void save()}>{busy ? "Saving…" : "Save"}</button></>}>
+    <Dialog open onClose={onClose} title={identity.id ? t("Edit identity") : t("New identity")} size="lg" footer={<><button className="btn" onClick={onClose}>{t("Cancel")}</button><button className="btn btn-primary" disabled={busy} onClick={() => void save()}>{busy ? t("Saving…") : t("Save")}</button></>}>
       <div className="field-row">
         <div className="field"><label>{t("Display name")}</label><input className="input" value={name} onChange={(e) => setName(e.target.value)} /></div>
         <div className="field"><label>{t("Email address")}</label><input className="input" type="email" value={email} disabled={Boolean(identity.id)} onChange={(e) => setEmail(e.target.value)} /></div>