Add a language-switch system with per-language files

Introduce a hand-rolled i18n layer across all three UIs, each reading its
text from per-language JSON files (English base + Polish + Danish). Nothing
in the converted screens hardcodes English any more.

- Web App (Vue): src/i18n/{en,pl,da}.json + index.js exposing t()/tSplit(),
  reactive to the signed-in profile locale. Every view, component, form and
  the status labels in lib/format.js go through t().
- API Server panel (Vue): src/i18n/ with its own localStorage-persisted
  language (the panel has no user profile) and a header language picker.
  Chrome, cards, login and API section titles translated; endpoint reference
  descriptions intentionally kept in English. Rebuilt embedded dist.
- Phone App (Flutter): assets/i18n/ + lib/i18n.dart loaded at startup,
  driven by AppSettings.locale. Nav, login, lock, dashboard, the full
  Settings panel (incl. language picker) and format.dart status labels
  translated; remaining detail screens fall back to English.

Language = the language half of the existing BCP-47 locale; the region half
still drives date/number/currency formatting. Missing keys fall back to
English, and plurals use Intl.PluralRules / Intl.plural so Polish gets the
correct one/few/many forms. Settings flags languages without a translation.

Tests updated to assert the localized (Polish) status wording; all pass.
See TRANSLATIONS.md for the format and how to add a language.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

API Server/panel/src/components/PocketBaseCard.vue

@@ -1,6 +1,7 @@
 <script setup>
 import { ref, onMounted } from "vue";
 import { request } from "../api";
+import { t } from "../i18n";
 
 // Superadmin-only: retarget the PocketBase this server talks to. The change is
 // applied at runtime AND persisted to the server's .env, so it survives a
@@ -37,10 +38,10 @@ async function test() {
       body: form.value,
     });
     notice.value = probe.value.superuser
-      ? "Connection OK — superuser authenticated."
+      ? t("pocketbase.testOk")
       : probe.value.reachable
-        ? "PocketBase is reachable, but the service account did not authenticate."
-        : "PocketBase is not reachable at that address.";
+        ? t("pocketbase.testReachableNoAuth")
+        : t("pocketbase.testUnreachable");
   } catch (e) {
     error.value = e.message;
   } finally {
@@ -57,7 +58,7 @@ async function save() {
     cfg.value = out.config;
     probe.value = out.config.probe;
     form.value.adminPassword = "";
-    notice.value = out.warning || "Saved. The server is now using this PocketBase.";
+    notice.value = out.warning || t("pocketbase.savedNotice");
   } catch (e) {
     error.value = e.message;
   } finally {
@@ -70,8 +71,8 @@ async function save() {
   <div class="dh-card overflow-hidden">
     <div class="flex items-center justify-between border-b border-subtle px-5 py-4">
       <div>
-        <div class="text-base font-bold tracking-[-0.02em] text-strong">PocketBase</div>
-        <p class="mt-0.5 text-xs text-muted">Database connection used by every endpoint</p>
+        <div class="text-base font-bold tracking-[-0.02em] text-strong">{{ t("pocketbase.title") }}</div>
+        <p class="mt-0.5 text-xs text-muted">{{ t("pocketbase.subtitle") }}</p>
       </div>
       <span
         v-if="probe"
@@ -83,30 +84,30 @@ async function save() {
             : 'bg-danger-soft text-danger'"
       >
         <span class="h-1.5 w-1.5 rounded-full bg-current"></span>
-        {{ probe.superuser ? "connected" : probe.reachable ? "no superuser" : "unreachable" }}
+        {{ probe.superuser ? t("pocketbase.connected") : probe.reachable ? t("pocketbase.noSuperuser") : t("pocketbase.unreachable") }}
       </span>
     </div>
 
     <div class="flex flex-col gap-4 px-5 py-4">
       <div>
-        <label class="dh-label" for="pb-url">Base URL</label>
+        <label class="dh-label" for="pb-url">{{ t("pocketbase.baseUrl") }}</label>
         <input id="pb-url" v-model="form.url" class="dh-input" placeholder="http://10.2.1.10:8027" />
       </div>
 
       <div class="grid gap-4 sm:grid-cols-2">
         <div>
-          <label class="dh-label" for="pb-email">Superuser email</label>
+          <label class="dh-label" for="pb-email">{{ t("pocketbase.superuserEmail") }}</label>
           <input id="pb-email" v-model="form.adminEmail" class="dh-input" autocomplete="off" />
         </div>
         <div>
-          <label class="dh-label" for="pb-password">Superuser password</label>
+          <label class="dh-label" for="pb-password">{{ t("pocketbase.superuserPassword") }}</label>
           <input
             id="pb-password"
             v-model="form.adminPassword"
             class="dh-input"
             type="password"
             autocomplete="new-password"
-            :placeholder="cfg?.adminConfigured ? 'unchanged' : 'not set'"
+            :placeholder="cfg?.adminConfigured ? t('pocketbase.passwordUnchanged') : t('pocketbase.passwordNotSet')"
           />
         </div>
       </div>
@@ -116,10 +117,10 @@ async function save() {
       <p v-if="error" class="rounded-control bg-danger-soft px-3 py-2 text-xs text-danger">{{ error }}</p>
 
       <div class="flex items-center gap-2">
-        <button class="dh-btn" :disabled="busy" @click="save">Save &amp; apply</button>
-        <button class="dh-btn-ghost" :disabled="busy" @click="test">Test connection</button>
+        <button class="dh-btn" :disabled="busy" @click="save">{{ t("pocketbase.saveApply") }}</button>
+        <button class="dh-btn-ghost" :disabled="busy" @click="test">{{ t("pocketbase.testConnection") }}</button>
         <span class="flex-1"></span>
-        <span class="eyebrow">persisted to .env</span>
+        <span class="eyebrow">{{ t("pocketbase.persistedEnv") }}</span>
       </div>
     </div>
   </div>