refactor(tui): store-driven turn state + slash registry + module split

Hoist turn state from a 286-line hook into $turnState atom + turnController
singleton. createGatewayEventHandler becomes a typed dispatch over the
controller; its ctx shrinks from 30 fields to 5. Event-handler refs and 16
threaded actions are gone.

Fold three createSlash*Handler factories into a data-driven SlashCommand[]
registry under slash/commands/{core,session,ops}.ts. Aliases are data;
findSlashCommand does name+alias lookup. Shared guarded/guardedErr combinator
in slash/guarded.ts.

Split constants.ts + app/helpers.ts into config/ (timing/limits/env),
content/ (faces/placeholders/hotkeys/verbs/charms/fortunes), domain/ (roles/
details/messages/paths/slash/viewport/usage), protocol/ (interpolation/paste).

Type every RPC response in gatewayTypes.ts (26 new interfaces); drop all
`(r: any)` across slash + main app.

Shrink useMainApp from 1216 -> 646 lines by extracting useSessionLifecycle,
useSubmission, useConfigSync. Add <Fg> themed primitive and strip ~50
`as any` color casts.

Tests: 50 passing. Build + type-check clean.

ui-tui/src/app/useConfigSync.ts

@@ -0,0 +1,84 @@
+import { useEffect, useRef } from 'react'
+
+import { resolveDetailsMode } from '../domain/details.js'
+import type {
+  ConfigFullResponse,
+  ConfigMtimeResponse,
+  ReloadMcpResponse,
+  VoiceToggleResponse
+} from '../gatewayTypes.js'
+
+import type { GatewayRpc } from './interfaces.js'
+import { turnController } from './turnController.js'
+import { patchUiState } from './uiStore.js'
+
+const MTIME_POLL_MS = 5000
+
+const applyDisplay = (cfg: ConfigFullResponse | null, setBell: (v: boolean) => void) => {
+  const display = cfg?.config?.display ?? {}
+
+  setBell(!!display.bell_on_complete)
+  patchUiState({
+    compact: !!display.tui_compact,
+    detailsMode: resolveDetailsMode(display),
+    statusBar: display.tui_statusbar !== false
+  })
+}
+
+export interface UseConfigSyncOptions {
+  rpc: GatewayRpc
+  setBellOnComplete: (v: boolean) => void
+  setVoiceEnabled: (v: boolean) => void
+  sid: null | string
+}
+
+export function useConfigSync({ rpc, setBellOnComplete, setVoiceEnabled, sid }: UseConfigSyncOptions) {
+  const mtimeRef = useRef(0)
+
+  useEffect(() => {
+    if (!sid) {
+      return
+    }
+
+    rpc<VoiceToggleResponse>('voice.toggle', { action: 'status' }).then(r => setVoiceEnabled(!!r?.enabled))
+    rpc<ConfigMtimeResponse>('config.get', { key: 'mtime' }).then(r => {
+      mtimeRef.current = Number(r?.mtime ?? 0)
+    })
+    rpc<ConfigFullResponse>('config.get', { key: 'full' }).then(r => applyDisplay(r, setBellOnComplete))
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [rpc, sid])
+
+  useEffect(() => {
+    if (!sid) {
+      return
+    }
+
+    const id = setInterval(() => {
+      rpc<ConfigMtimeResponse>('config.get', { key: 'mtime' }).then(r => {
+        const next = Number(r?.mtime ?? 0)
+
+        if (!mtimeRef.current) {
+          if (next) {
+            mtimeRef.current = next
+          }
+
+          return
+        }
+
+        if (!next || next === mtimeRef.current) {
+          return
+        }
+
+        mtimeRef.current = next
+
+        rpc<ReloadMcpResponse>('reload.mcp', { session_id: sid }).then(
+          r => r && turnController.pushActivity('MCP reloaded after config change')
+        )
+        rpc<ConfigFullResponse>('config.get', { key: 'full' }).then(r => applyDisplay(r, setBellOnComplete))
+      })
+    }, MTIME_POLL_MS)
+
+    return () => clearInterval(id)
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [rpc, sid])
+}