Add -R restart operation for timer and service jobs

Resets the countdown for timer jobs and restarts the process for
service jobs. Disabled jobs are refused with a clear error message.
Accepts hex ID or name like all other management operations.

- restartJob() function with disabled-job guard
- getopts R:, manage_count, mutual-exclusion error messages updated
- 9 new tests in test.sh (112 total), 1 new tape command (24 total)
- README options table, names prose, and future-ideas checklist updated

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

demo/all-features.tape

@@ -109,6 +109,19 @@ Sleep 500ms
 Enter
 Sleep 2s
 
+# ── Restart ───────────────────────────────────────────────────
+
+Hide
+Type "./demo/note.sh 'Restart a job — resets the timer countdown'"
+Enter
+Sleep 500ms
+Show
+Sleep 1s
+Type "systab -R healthcheck_home"
+Sleep 500ms
+Enter
+Sleep 2s
+
 # ── Notifications ─────────────────────────────────────────────
 
 Hide