Migrate to new @welshman/domain + instance-based @welshman/app API

Adopts the rewritten welshman API: the removed @welshman/util helpers
(Profile/List/Room/Handler/Encryptable) are now Reader/Builder classes in
@welshman/domain, and @welshman/app dropped its global singletons for an App
instance + app.use(Plugin) registry.

- src/app/welshman.ts is now the app bootstrap + session-state module (one shared
  App instance, multi-account sessions/login, app-wide reactive views) rather than
  a compat shim re-exporting the old globals.
- Rewrote ~100 callers to use app.use(Plugin) directly (thunks, profiles, relays,
  rooms, zaps, tags, wot, feeds, sync); thunk helpers are now thunk methods.
- Added @welshman/domain dependency.
- Resolved residual gaps (storage hydration via plugin.onItem/wrapManager/Plaintext,
  relay-list mutators, search-relay list, outbox #d filter).

Best-effort: no toolchain/linking available, so this is not build- or
type-checked. Remaining judgment calls are flagged with TODO(welshman-migration).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BsMjvv7krpZeHK1Njeneru

src/app/components/Profile.svelte

@@ -1,8 +1,9 @@
 <script lang="ts">
   import * as nip19 from "nostr-tools/nip19"
   import {removeUndefined} from "@welshman/lib"
-  import {displayPubkey} from "@welshman/util"
-  import {deriveHandleForPubkey, displayHandle, deriveProfileDisplay} from "@welshman/app"
+  import {displayPubkey, displayNip05} from "@welshman/util"
+  import {Handles, Profiles} from "@welshman/app"
+  import {app} from "@app/welshman"
   import Icon from "@lib/components/Icon.svelte"
   import Button from "@lib/components/Button.svelte"
   import ProfileCircle from "@app/components/ProfileCircle.svelte"
@@ -23,8 +24,8 @@
   const {pubkey, url, showPubkey, inert, avatarSize = 10}: Props = $props()
 
   const relays = removeUndefined([url])
-  const profileDisplay = deriveProfileDisplay(pubkey, relays)
-  const handle = deriveHandleForPubkey(pubkey)
+  const profileDisplay = app.use(Profiles).display(pubkey, relays).$
+  const handle = app.use(Handles).forPubkey(pubkey).$
 
   const openProfile = () => {
     pushModal(ProfileDetail, {pubkey, url})
@@ -58,7 +59,7 @@
     </div>
     {#if $handle}
       <div class="overflow-hidden text-ellipsis text-sm opacity-75">
-        {displayHandle($handle)}
+        {displayNip05($handle?.nip05)}
       </div>
     {/if}
     {#if showPubkey}