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/fortunes.ts

@@ -0,0 +1,40 @@
+const FORTUNES = [
+  'you are one clean refactor away from clarity',
+  'a tiny rename today prevents a huge bug tomorrow',
+  'your next commit message will be immaculate',
+  'the edge case you are ignoring is already solved in your head',
+  'minimal diff, maximal calm',
+  'today favors bold deletions over new abstractions',
+  'the right helper is already in your codebase',
+  'you will ship before overthinking catches up',
+  'tests are about to save your future self',
+  'your instincts are correctly suspicious of that one branch'
+]
+
+const LEGENDARY_FORTUNES = [
+  'legendary drop: one-line fix, first try',
+  'legendary drop: every flaky test passes cleanly',
+  'legendary drop: your diff teaches by itself'
+]
+
+const hash = (input: string) => {
+  let out = 2166136261
+
+  for (let i = 0; i < input.length; i++) {
+    out ^= input.charCodeAt(i)
+    out = Math.imul(out, 16777619)
+  }
+
+  return out >>> 0
+}
+
+const fromScore = (score: number) => {
+  const rare = score % 20 === 0
+  const bag = rare ? LEGENDARY_FORTUNES : FORTUNES
+
+  return `${rare ? '🌟' : '🔮'} ${bag[score % bag.length]}`
+}
+
+export const randomFortune = () => fromScore(Math.floor(Math.random() * 0x7fffffff))
+
+export const dailyFortune = (seed: null | string) => fromScore(hash(`${seed || 'anon'}|${new Date().toDateString()}`))