Merge public ihasmail: the app's name comes from APP_NAME everywhere

Upstream's {app} placeholder (#406) replaces most of the fork's own
renamed strings: the user menu, the About heading and its version line
now say INBUXA because APP_NAME does, not because the fork wrote it in.

Kept from the fork: inbuxa.org rather than ihasmail.org, no Documentation
entry until INBUXA has its own, the INBUXA mark and wordmark, the "Built
on ihasmail" credit, and the About note that says nothing about the
server software. DEFAULT_APP_NAME stays INBUXA.

The credit's placeholder is {project} now, so the name of the project is
not spelled inside a key that upstream's new test reads as a hard-coded
app name.

web/src/views/settings/AboutSettings.tsx

@@ -1,4 +1,5 @@
 import { useSession } from "@/store/session";
+import { useAppName } from "@/lib/brand";
 import { client } from "@/jmap/client";
 import { APP_VERSION, SOURCE_ARCHIVE, SOURCE_ID } from "@/lib/version";
 import { withBase } from "@/lib/basePath";
@@ -6,22 +7,25 @@ import { t, tNode } from "@/lib/i18n";
 import { InbuxaWordmark } from "@/ui/InbuxaWordmark";
 
 export function AboutSettings() {
+  const appName = useAppName();
   const session = useSession((s) => s.session);
   const caps = Object.keys(session?.capabilities ?? {});
   // The exact source of this build, written next to the app by the build.
   return (
     <div>
       {/* ihasmail-inbuxa: INBUXA's webmail, built on ihasmail. The version and
-          source are this build's, the AGPL's offer; ihasmail keeps its credit. */}
-      <h1>{t("About INBUXA webmail")}</h1>
-      <p className="lead">{tNode("A fast, friendly, open-source webmail for {server}, built on JMAP.", { server: <span className="notranslate" translate="no">INBUXA</span> })}</p>
+          source are this build's, the AGPL's offer; ihasmail keeps its credit.
+          The name comes from APP_NAME now, so a renamed deployment is named
+          here too. */}
+      <h1>{t("About {app}", { app: appName })}</h1>
+      <p className="lead">{tNode("A fast, friendly, open-source webmail for {server}, built on JMAP.", { server: <span className="notranslate" translate="no">{appName}</span> })}</p>
       <div className="row" style={{ gap: 16, alignItems: "center", marginBottom: 16 }}>
         <img src={withBase("/img/inbuxa-mark.png")} alt="" width={80} />
         <div>
           <InbuxaWordmark height={26} />
           {/* A product name and a version string: neither is a word to translate. */}
-          <div style={{ fontWeight: 700 }} className="notranslate" translate="no">INBUXA webmail v{APP_VERSION}</div>
-          <div className="hint">{tNode("Built on {ihasmail}", { ihasmail: <a href="https://ihasmail.org" target="_blank" rel="noopener noreferrer" className="notranslate" translate="no">ihasmail</a> })}</div>
+          <div style={{ fontWeight: 700 }} className="notranslate" translate="no">{appName} webmail v{APP_VERSION}</div>
+          <div className="hint">{tNode("Built on {project}", { project: <a href="https://ihasmail.org" target="_blank" rel="noopener noreferrer" className="notranslate" translate="no">ihasmail</a> })}</div>
           <div className="hint">{tNode("AGPL-3.0-or-later · {source}", { source: <a href={withBase(SOURCE_ARCHIVE)} target="_blank" rel="noopener noreferrer" className="notranslate" translate="no">source.tar.gz ({SOURCE_ID})</a> })}</div>
         </div>
       </div>
@@ -36,7 +40,7 @@ export function AboutSettings() {
         </tbody>
       </table>
       <p className="hint" style={{ marginTop: 6 }}>{t("This webmail works with the INBUXA mail server, and sign-in refuses a server that doesn't offer what it needs.")}</p>
-      <p className="hint">{tNode("ihasmail's own version is the date of the commit it was built from, followed by where that commit came from: {example} was built from a commit dated the 30th of August 2026 that arrived through pull request 129. A commit that did not come through one carries its short SHA instead — {sha}. The version deliberately says nothing about the mail server; what this build needs from the server is the line above.", { example: <strong className="notranslate" translate="no">v2026.8.30+pr129</strong>, sha: <code>+g1fa6578</code> })}</p>
+      <p className="hint">{tNode("{app}'s own version is the date of the commit it was built from, followed by where that commit came from: {example} was built from a commit dated the 30th of August 2026 that arrived through pull request 129. A commit that did not come through one carries its short SHA instead — {sha}. The version deliberately says nothing about the mail server; what this build needs from the server is the line above.", { example: <strong className="notranslate" translate="no">v2026.8.30+pr129</strong>, sha: <code>+g1fa6578</code> }, { app: appName })}</p>
       <h2>{t("Server capabilities")}</h2>
       <div className="row wrap gap-4">
         {caps.map((c) => <span key={c} className="chip mono" style={{ fontSize: ".78em" }}>{c.replace("urn:ietf:params:jmap:", "")}</span>)}