feat(KB-045): add scheduled tasks automation system

- Add AutomationStore and core automation types for cron-based scheduling
- Implement CronRunner engine for executing scheduled automations
- Add REST API routes for CRUD operations on automations
- Create UI components: ScheduleCard, ScheduleForm, and ScheduledTasksModal
- Integrate scheduled tasks into dashboard App.tsx and CLI dashboard command
- Add comprehensive tests for store, runner, API, and UI components
- Include changeset for the new scheduled tasks feature

packages/core/src/automation.ts

@@ -0,0 +1,79 @@
+/** Schedule type presets plus a custom cron option. */
+export type ScheduleType = "hourly" | "daily" | "weekly" | "monthly" | "custom";
+
+/** Mapping from preset schedule types to their cron expressions. */
+export const AUTOMATION_PRESETS: Record<Exclude<ScheduleType, "custom">, string> = {
+  hourly: "0 * * * *",
+  daily: "0 0 * * *",
+  weekly: "0 0 * * 1",
+  monthly: "0 0 1 * *",
+};
+
+/** Result of a single automation run. */
+export interface AutomationRunResult {
+  success: boolean;
+  output: string;
+  error?: string;
+  startedAt: string;
+  completedAt: string;
+}
+
+/** A scheduled automation task. */
+export interface ScheduledTask {
+  /** Unique identifier for this schedule (UUID). */
+  id: string;
+  /** Human-readable name for this schedule. */
+  name: string;
+  /** Optional description of what this schedule does. */
+  description?: string;
+  /** The type of schedule — preset or custom. */
+  scheduleType: ScheduleType;
+  /** The cron expression (auto-derived from preset or user-supplied for custom). */
+  cronExpression: string;
+  /** The shell command to execute. */
+  command: string;
+  /** Whether this schedule is currently active. */
+  enabled: boolean;
+  /** ISO-8601 timestamp of the last run start, if any. */
+  lastRunAt?: string;
+  /** Result of the most recent run, if any. */
+  lastRunResult?: AutomationRunResult;
+  /** ISO-8601 timestamp of the next scheduled run. */
+  nextRunAt?: string;
+  /** Total number of runs executed. */
+  runCount: number;
+  /** Per-schedule execution timeout in milliseconds. Default: 300000 (5 min). */
+  timeoutMs?: number;
+  /** History of recent run results (most recent first, capped at 50). */
+  runHistory: AutomationRunResult[];
+  /** ISO-8601 timestamp of when this schedule was created. */
+  createdAt: string;
+  /** ISO-8601 timestamp of when this schedule was last updated. */
+  updatedAt: string;
+}
+
+/** Input for creating a new scheduled task. */
+export interface ScheduledTaskCreateInput {
+  name: string;
+  description?: string;
+  scheduleType: ScheduleType;
+  /** Required for 'custom' type; ignored for presets (auto-derived). */
+  cronExpression?: string;
+  command: string;
+  enabled?: boolean;
+  timeoutMs?: number;
+}
+
+/** Input for updating an existing scheduled task. */
+export interface ScheduledTaskUpdateInput {
+  name?: string;
+  description?: string;
+  scheduleType?: ScheduleType;
+  cronExpression?: string;
+  command?: string;
+  enabled?: boolean;
+  timeoutMs?: number;
+}
+
+/** Maximum number of run history entries to retain per schedule. */
+export const MAX_RUN_HISTORY = 50;