schedule: add paseo schedule update to edit schedules in place (#694)

* schedule: add `paseo schedule update` to edit schedules in place

Editing a schedule today requires delete+recreate, losing run history
and the schedule id. This adds an additive RPC and CLI command that
patches name, prompt, cadence, new-agent target fields, max-runs, and
expires-in without touching runs or in-flight executions. nextRunAt is
recomputed only when the cadence actually changes.

* schedule(cli): share cadence flag parser between create and update

Both paths were turning --every/--cron into a ScheduleCadence with
near-identical code. Extract `parseCadenceFromFlags` so the literals
and the exclusivity check live in one place; create wraps it to
require a value, update lets it stay optional.

packages/cli/src/commands/schedule/update.ts

@@ -0,0 +1,66 @@
+import type { Command } from "commander";
+import type { ListResult } from "../../output/index.js";
+import {
+  createScheduleInspectRows,
+  createScheduleInspectSchema,
+  type ScheduleInspectRow,
+} from "./schema.js";
+import {
+  connectScheduleClient,
+  parseScheduleUpdateInput,
+  toScheduleCommandError,
+  type ScheduleCommandOptions,
+} from "./shared.js";
+
+export interface ScheduleUpdateOptions extends ScheduleCommandOptions {
+  every?: string;
+  cron?: string;
+  name?: string;
+  prompt?: string;
+  provider?: string;
+  model?: string;
+  mode?: string;
+  cwd?: string;
+  maxRuns?: string;
+  noMaxRuns?: boolean;
+  expiresIn?: string;
+  noExpiresIn?: boolean;
+}
+
+export async function runUpdateCommand(
+  id: string,
+  options: ScheduleUpdateOptions,
+  _command: Command,
+): Promise<ListResult<ScheduleInspectRow>> {
+  const input = parseScheduleUpdateInput({
+    id,
+    every: options.every,
+    cron: options.cron,
+    name: options.name,
+    prompt: options.prompt,
+    provider: options.provider,
+    model: options.model,
+    mode: options.mode,
+    cwd: options.cwd,
+    maxRuns: options.maxRuns,
+    expiresIn: options.expiresIn,
+    clearMaxRuns: options.noMaxRuns,
+    clearExpires: options.noExpiresIn,
+  });
+  const { client } = await connectScheduleClient(options.host);
+  try {
+    const payload = await client.scheduleUpdate(input);
+    if (payload.error || !payload.schedule) {
+      throw new Error(payload.error ?? `Failed to update schedule: ${id}`);
+    }
+    return {
+      type: "list",
+      data: createScheduleInspectRows(payload.schedule),
+      schema: createScheduleInspectSchema(payload.schedule),
+    };
+  } catch (error) {
+    throw toScheduleCommandError("SCHEDULE_UPDATE_FAILED", "update schedule", error);
+  } finally {
+    await client.close().catch(() => {});
+  }
+}