Add a Schedules screen to manage recurring agents (#1246)

* feat: add Schedules screen to manage scheduled agents

Adds a Schedules section in the sidebar header (below Sessions) for viewing
and managing new-agent schedules: recurring jobs that spawn an agent on a
cron or interval cadence.

- Borderless table showing provider icon, model, cadence, next run, and
  status, with row actions to edit, pause/resume, run now, and delete.
- Create/edit sheet that reuses the agent provider/model/mode/working-
  directory pickers, plus an interval/cron cadence editor with presets,
  validation, and a UTC preview.
- Responsive: hover-revealed row actions on desktop, an always-visible
  action menu on mobile.
- Data layer over the existing schedule RPCs (list/create/update/pause/
  resume/delete/run-once) with optimistic pause, resume, and delete.

Scope is limited to new-agent schedules for now.

* Make the schedule form controls visually consistent

Merge the provider and model pickers into the single nested selector the
draft screen uses, render it as a full-width field, mute the placeholder,
proportion the cadence segmented controls, unify the cron preset chips,
and route the sheet scroll through the themed scrollbar.

* Address schedules review feedback

* Translate schedule hook client fallback errors

* Make schedules global and project scoped

* Stabilize project settings transport E2E

* Reset schedule model on cross-host project change

* Reject malformed cron step expressions

* Tighten schedules project query freshness

* refactor(schedules): clean up review feedback

* test(schedules): extract fake host setup

* refactor(schedules): share cron expression parsing

Use one structural cron parser for app previews and daemon cadence validation so the accepted grammar cannot drift between surfaces.

Remove the unused host-scoped schedules redirect while keeping the global schedules route.

packages/app/src/i18n/resources/ar.ts

@@ -789,6 +789,7 @@ export const ar: TranslationResources = {
     },
     sections: {
       sessions: "السجل",
+      schedules: "الجداول",
     },
     worktreeSetup: {
       title: "إعداد البرامج النصية لشجرة العمل",

packages/app/src/i18n/resources/en.ts

@@ -796,6 +796,7 @@ export const en = {
     },
     sections: {
       sessions: "History",
+      schedules: "Schedules",
     },
     worktreeSetup: {
       title: "Set up worktree scripts",

packages/app/src/i18n/resources/es.ts

@@ -816,6 +816,7 @@ export const es: TranslationResources = {
     },
     sections: {
       sessions: "Historial",
+      schedules: "Horarios",
     },
     worktreeSetup: {
       title: "Configurar secuencias de comandos del árbol de trabajo",

packages/app/src/i18n/resources/fr.ts

@@ -815,6 +815,7 @@ export const fr: TranslationResources = {
     },
     sections: {
       sessions: "Historique",
+      schedules: "Planifications",
     },
     worktreeSetup: {
       title: "Configurer les scripts d'arbre de travail",

packages/app/src/i18n/resources/ja.ts

@@ -801,6 +801,7 @@ export const ja: TranslationResources = {
     },
     sections: {
       sessions: "履歴",
+      schedules: "スケジュール",
     },
     worktreeSetup: {
       title: "ワークツリースクリプトを設定",

packages/app/src/i18n/resources/pt-BR.ts

@@ -807,6 +807,7 @@ export const ptBR: TranslationResources = {
     },
     sections: {
       sessions: "Histórico",
+      schedules: "Agendamentos",
     },
     worktreeSetup: {
       title: "Configurar scripts de worktree",

packages/app/src/i18n/resources/ru.ts

@@ -808,6 +808,7 @@ export const ru: TranslationResources = {
     },
     sections: {
       sessions: "История",
+      schedules: "Расписания",
     },
     worktreeSetup: {
       title: "Настройка сценариев рабочего дерева",

packages/app/src/i18n/resources/zh-CN.ts

@@ -783,6 +783,7 @@ export const zhCN: TranslationResources = {
     },
     sections: {
       sessions: "历史",
+      schedules: "计划",
     },
     worktreeSetup: {
       title: "设置 worktree scripts",