The plugin runtime received the active locale (init payload + 'locale-change')
and plugins could declare a `locales` map, but none of it was usable: the
locales never reached the runtime, and buildPluginApi exposed no i18n. So
plugin code calling pluginApi.i18n.t(...) (as the External Link Warning plugin
does) always got undefined and fell back to English.
Thread plugin locales end to end and surface an i18n API:
- ServerPlugin gains `locales`; the upload route persists manifest.locales
(alongside configSchema/settingsSchema), and /api/plugins surfaces it to the
client so it flows registry -> client -> sandbox host-bridge -> runtime.
- runtime sets __PLUGIN_LOCALE__ at init (not only on later 'locale-change')
and buildPluginApi exposes `i18n.locale` + `i18n.t(key, vars)` resolving
against the plugin's declared locales (manifest.locales) with English/key
fallback and {placeholder} interpolation.
Lets any sandboxed plugin localize its strings from its manifest.
Makes every client-side fetch('/api/...') call respect the mount prefix
when Bulwark is served behind a reverse proxy at a sub-path (e.g.
`/webmail`).
### Problem
`getPathPrefix()` (added in 1.4.13 by #XXX / d762b94) already fixes
router navigation and redirect URIs for reverse-proxy deployments.
Client-side `fetch()` calls, though, still target the browser origin:
await fetch('/api/foo')
// Browser at /webmail/en/inbox → hits /api/foo (not proxied → 404)
That means the login flow, session establishment, settings save, plugin
loader, calendar import, etc. all break the moment you front Bulwark
with nginx (or any proxy) at a sub-path.
### Fix
Add `apiFetch(input, init)` next to `getPathPrefix()` in
`lib/browser-navigation.ts`. It prepends the mount prefix to any
absolute path at call time:
await apiFetch('/api/foo')
// /webmail/en/inbox → /webmail/api/foo
// /en/inbox → /api/foo
Same runtime-detection model as `getPathPrefix()` — the built bundle
works at any mount point without rebuilding or env-var config.
Protocol-relative (`//cdn...`) and absolute (`https://...`) URLs pass
through unchanged. Server-side route handlers are untouched (the mount
prefix is a browser-only concept).
### Migration
Mechanical rewrite of every client-side `fetch('/api/...')` call in
hooks/, lib/, stores/, components/, app/ — 99 call sites across
26 files. `route.ts` handlers and other server-only files are skipped.
### Compat
- No behaviour change when mounted at `/` (the common case): an empty
prefix + raw path is identical to raw path.
- No new config knobs, env vars, or build flags.
- Supersedes PR #181 (which required a build-time `NEXT_PUBLIC_BASE_PATH`)
— will close#181 after this lands.
### Testing
Should run the existing suite; smoke-tested by Jabali Panel which
reverse-proxies Bulwark at `/webmail/` (https://github.com/shukiv/jabali-panel).
