Implement cron job management tools and types

- Added `JobType`, `SessionTarget`, `Schedule`, `DeliveryConfig`, `CronJob`, `CronRun`, and `CronJobPatch` types in `src/cron/types.rs` for cron job configuration and management.
- Introduced `CronAddTool`, `CronListTool`, `CronRemoveTool`, `CronRunTool`, `CronRunsTool`, and `CronUpdateTool` in `src/tools` for adding, listing, removing, running, and updating cron jobs.
- Updated the `run` function in `src/daemon/mod.rs` to conditionally start the scheduler based on the cron configuration.
- Modified command-line argument parsing in `src/lib.rs` and `src/main.rs` to support new cron job commands.
- Enhanced the onboarding wizard in `src/onboard/wizard.rs` to include cron configuration.
- Added tests for cron job tools to ensure functionality and error handling.

src/lib.rs

@@ -147,6 +147,23 @@ pub enum CronCommands {
     Add {
         /// Cron expression
         expression: String,
+        /// Optional IANA timezone (e.g. America/Los_Angeles)
+        #[arg(long)]
+        tz: Option<String>,
+        /// Command to run
+        command: String,
+    },
+    /// Add a one-shot scheduled task at an RFC3339 timestamp
+    AddAt {
+        /// One-shot timestamp in RFC3339 format
+        at: String,
+        /// Command to run
+        command: String,
+    },
+    /// Add a fixed-interval scheduled task
+    AddEvery {
+        /// Interval in milliseconds
+        every_ms: u64,
         /// Command to run
         command: String,
     },