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/SpaceMembers.svelte

@@ -1,6 +1,7 @@
 <script lang="ts">
   import {ManagementMethod} from "@welshman/util"
-  import {manageRelay, displayProfileByPubkey} from "@welshman/app"
+  import {RelayManagement, Profiles} from "@welshman/app"
+  import {app} from "@app/welshman"
   import MenuDots from "@assets/icons/menu-dots.svg?dataurl"
   import UserMinus from "@assets/icons/user-minus.svg?dataurl"
   import MinusCircle from "@assets/icons/minus-circle.svg?dataurl"
@@ -60,9 +61,9 @@
   const unallowMember = (pubkey: string) =>
     pushModal(Confirm, {
       title: "Remove User",
-      message: `Are you sure you want to remove @${displayProfileByPubkey(pubkey)} from the space?`,
+      message: `Are you sure you want to remove @${app.use(Profiles).display(pubkey).get()} from the space?`,
       confirm: async () => {
-        const {error} = await manageRelay(url, {
+        const {error} = await app.use(RelayManagement).post(url, {
           method: ManagementMethod.UnallowPubkey,
           params: [pubkey],
         })
@@ -79,9 +80,9 @@
   const banMember = (pubkey: string) =>
     pushModal(Confirm, {
       title: "Ban User",
-      message: `Are you sure you want to ban @${displayProfileByPubkey(pubkey)} from the space?`,
+      message: `Are you sure you want to ban @${app.use(Profiles).display(pubkey).get()} from the space?`,
       confirm: async () => {
-        const {error} = await manageRelay(url, {
+        const {error} = await app.use(RelayManagement).post(url, {
           method: ManagementMethod.BanPubkey,
           params: [pubkey],
         })