Add loop-scoped holiday list support

OpenJibo/docs/holiday-architecture.md

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+# Holiday Architecture
+
+Pegasus exposed holidays as a loop-scoped list synchronized into `/jibo/holidays`.
+
+In OpenJibo, the holiday path now follows the same broad model:
+
+- system holidays come from a live holiday source
+- custom holidays are loop-scoped
+- suppressed holidays are represented as disabled records
+- the cloud protocol returns the merged list for `PersonListHolidays`
+
+Current behavior:
+
+- `Person/ListHolidays` uses the loop from the request when available
+- if no loop is supplied, the cloud falls back safely instead of throwing
+- the merged list is built from system holidays plus any custom loop entries
+
+Notes:
+
+- `IsEnabled = false` can be used to suppress a holiday later
+- birthdays and other personal events can be added as loop-scoped custom records
+- the current system holiday source uses Nager.Date with a safe local fallback for uptime