fix: use dynamic imports for @e4a/pg-js to support SSR

pg-js bundles WASM and browser APIs that can't load during SSR.
Use lazy getPostGuard() and dynamic import() for error classes
so the module is only loaded in the browser.

Author: rubenhensen

src/lib/components/fallback/Decrypt.svelte

@@ -15,8 +15,7 @@
 
     import { locale, _ } from 'svelte-i18n'
 
-    import { pg } from '$lib/postguard'
-    import { IdentityMismatchError } from '@e4a/pg-js'
+    import { getPostGuard } from '$lib/postguard'
 
     import YiviQRCode from '$lib/components/filesharing/YiviQRCode.svelte'
     import Chip from '$lib/components/Chip.svelte'
@@ -129,9 +128,11 @@
 
     run(() => {
         if (decryptState === STATES.Uninit && readable) {
+            getPostGuard().then((pg) => {
             const o = pg.open({ data: readable })
             opened = o
-            o.inspect()
+            return o.inspect()
+            })
                 .then((info) => {
                     decryptState = STATES.Init
                     policies = info.policies

src/lib/components/filesharing/SendButton.svelte

@@ -1,11 +1,10 @@
 <script lang="ts">
     import { _, locale } from 'svelte-i18n'
     import { isValidPhoneNumber } from 'libphonenumber-js/mobile'
-    import { NetworkError } from '@e4a/pg-js'
 
     import yiviLogoDark from '$lib/assets/images/non-free/yivi-logo-dark.svg'
     import { EncryptionState, type EncryptState } from '$lib/types/filesharing/attributes'
-    import { pg } from '$lib/postguard'
+    import { getPostGuard } from '$lib/postguard'
     import { browser } from '$app/environment'
     import { isMobile } from '$lib/browser-detect'
     import YiviQRCode from './YiviQRCode.svelte'
@@ -92,6 +91,8 @@
         try {
             if (!canEncrypt()) return
 
+            const pg = await getPostGuard()
+
             // Build recipients
             const recipients = EncryptState.recipients.map(({ email, extra }) => {
                 if (extra.length > 0) {
@@ -146,6 +147,7 @@
                 EncryptState.selfAborted = false
                 EncryptState.encryptStartTime = 0
             } else {
+                const { NetworkError } = await import('@e4a/pg-js')
                 EncryptState.serverError = e instanceof NetworkError && e.status >= 500
                 EncryptState.encryptionState = EncryptionState.Error
             }

src/lib/postguard.ts

@@ -1,7 +1,15 @@
-import { PostGuard } from '@e4a/pg-js'
-import { PKG_URL, FILEHOST_URL } from '$lib/env'
+import type { PostGuard as PostGuardType } from '@e4a/pg-js'
 
-export const pg = new PostGuard({
-    pkgUrl: PKG_URL,
-    cryptifyUrl: FILEHOST_URL,
-})
+let instance: PostGuardType | null = null
+
+export async function getPostGuard(): Promise<PostGuardType> {
+    if (!instance) {
+        const { PostGuard } = await import('@e4a/pg-js')
+        const { PKG_URL, FILEHOST_URL } = await import('$lib/env')
+        instance = new PostGuard({
+            pkgUrl: PKG_URL,
+            cryptifyUrl: FILEHOST_URL,
+        })
+    }
+    return instance
+}

src/routes/debug/qr/+page.svelte

@@ -1,12 +1,13 @@
 <script lang="ts">
     import { onMount } from 'svelte'
     import YiviQRCode from '$lib/components/filesharing/YiviQRCode.svelte'
-    import { pg } from '$lib/postguard'
+    import { getPostGuard } from '$lib/postguard'
 
     onMount(async () => {
         // Initialize Yivi session for testing
         // Note: this page just displays a QR code component for visual testing.
         // The actual Yivi session is handled by pg-js when sign.yivi() is called.
+        const pg = await getPostGuard()
         console.log('QR test page loaded. PostGuard instance:', pg)
     })
 </script>

src/routes/download/+page.svelte

@@ -2,8 +2,7 @@
     import { onMount, tick } from 'svelte'
     import { browser, dev } from '$app/environment'
     import { _ } from 'svelte-i18n'
-    import { pg } from '$lib/postguard'
-    import { IdentityMismatchError, NetworkError } from '@e4a/pg-js'
+    import { getPostGuard } from '$lib/postguard'
     import type { DecryptFileResult, FriendlySender, InspectResult } from '@e4a/pg-js'
     import YiviQRCode from '$lib/components/filesharing/YiviQRCode.svelte'
     import FileList from '$lib/components/filesharing/FileList.svelte'
@@ -46,6 +45,7 @@
     async function startDownload() {
         downloadState = 'Downloading'
         try {
+            const pg = await getPostGuard()
             opened = pg.open({ uuid })
             const info: InspectResult = await opened.inspect()
 
@@ -55,6 +55,7 @@
 
             checkRecipients(info.recipients)
         } catch (e) {
+            const { NetworkError } = await import('@e4a/pg-js')
             if (e instanceof NetworkError && e.status >= 500) {
                 downloadState = 'ServerError'
             } else {
@@ -107,6 +108,7 @@
         } catch (e) {
             if (dev) console.error('[download] decrypt error:', e)
             err = String(e)
+            const { IdentityMismatchError, NetworkError } = await import('@e4a/pg-js')
             if (e instanceof IdentityMismatchError) {
                 downloadState = 'IdentityMismatch'
             } else if (e instanceof NetworkError && e.status >= 500) {