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/PollVotes.svelte

@@ -2,7 +2,9 @@
   import {onDestroy} from "svelte"
   import type {TrustedEvent} from "@welshman/util"
   import {POLL_RESPONSE} from "@welshman/util"
-  import {pubkey, publishThunk, abortThunk} from "@welshman/app"
+  import type {Thunk} from "@welshman/app"
+  import {Thunks} from "@welshman/app"
+  import {pubkey, app} from "@app/welshman"
   import {formatTimestampRelative} from "@welshman/lib"
   import {deriveEvents} from "@app/repository"
   import {pushToast} from "@app/toast"
@@ -50,7 +52,7 @@
 
   const publishSelection = (selection: string[]) => {
     if (activeThunk) {
-      abortThunk(activeThunk)
+      activeThunk.abort()
     }
 
     if (selection.length === 0) {
@@ -58,7 +60,7 @@
       return
     }
 
-    activeThunk = publishThunk({
+    activeThunk = app.use(Thunks).publish({
       relays: [url],
       event: makePollResponse({event, selectedIds: selection}),
       delay: publishDelay,
@@ -92,7 +94,7 @@
   }
 
   let selectedIds = $state<string[]>([])
-  let activeThunk: ReturnType<typeof publishThunk> | undefined
+  let activeThunk: Thunk | undefined
 
   $effect(() => {
     if (ownResponse) {
@@ -102,7 +104,7 @@
 
   onDestroy(() => {
     if (activeThunk) {
-      abortThunk(activeThunk)
+      activeThunk.abort()
     }
   })
 </script>