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/content/verbs.ts

@@ -0,0 +1,38 @@
+export const TOOL_VERBS: Record<string, string> = {
+  browser: 'browsing',
+  clarify: 'asking',
+  create_file: 'creating',
+  delegate_task: 'delegating',
+  delete_file: 'deleting',
+  execute_code: 'executing',
+  image_generate: 'generating',
+  list_files: 'listing',
+  memory: 'remembering',
+  patch: 'patching',
+  read_file: 'reading',
+  run_command: 'running',
+  search_code: 'searching',
+  search_files: 'searching',
+  terminal: 'terminal',
+  web_extract: 'extracting',
+  web_search: 'searching',
+  write_file: 'writing'
+}
+
+export const VERBS = [
+  'pondering',
+  'contemplating',
+  'musing',
+  'cogitating',
+  'ruminating',
+  'deliberating',
+  'mulling',
+  'reflecting',
+  'processing',
+  'reasoning',
+  'analyzing',
+  'computing',
+  'synthesizing',
+  'formulating',
+  'brainstorming'
+]