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/ProfileEdit.svelte

@@ -1,7 +1,6 @@
 <script lang="ts">
-  import type {Profile} from "@welshman/util"
-  import {makeProfile} from "@welshman/util"
-  import {pubkey, profilesByPubkey, waitForThunkError} from "@welshman/app"
+  import {Profile, ProfileBuilder} from "@welshman/domain"
+  import {pubkey, profilesByPubkey} from "@app/welshman"
   import AltArrowLeft from "@assets/icons/alt-arrow-left.svg?dataurl"
   import {errorMessage} from "@lib/util"
   import Icon from "@lib/components/Icon.svelte"
@@ -12,16 +11,28 @@
   import {pushToast} from "@app/toast"
   import {updateProfile} from "@app/profiles"
 
-  const profile = $profilesByPubkey.get($pubkey!) || makeProfile()
+  // The edit form binds to plain mutable fields (name/about/nip05/picture), so we
+  // hand it a plain values object rather than a Profile Reader. A Reader exposes its
+  // raw parsed content as `.values`; a fresh profile starts from an empty builder.
+  const reader = $profilesByPubkey.get($pubkey!)
+  const profile = reader instanceof Profile ? {...reader.values} : new ProfileBuilder().update({}).values
   const initialValues = {profile}
 
   const back = () => history.back()
 
+  // TODO(welshman-migration): `profile` here is a plain values object (the form binds
+  // mutable fields), not a Profile Reader. It is typed Profile to match ProfileEditForm's
+  // Values type and updateProfile's signature, both of which still say Profile; updateProfile
+  // routes a non-Reader through `new ProfileBuilder().update(profile)`. Confirm the intended
+  // values vs Reader contract once the shared types settle.
   const onsubmit = async ({profile}: {profile: Profile}) => {
     loading = true
 
     try {
-      const error = await waitForThunkError(updateProfile({profile}))
+      // TODO(welshman-migration): updateProfile is async (returns Promise<Thunk>); the old
+      // waitForThunkError shim did not await its arg. Awaiting the thunk first before
+      // .waitForError() — confirm this matches intended behavior.
+      const error = await (await updateProfile({profile})).waitForError()
 
       if (error) {
         pushToast({