feat(t-paliad-122): country+regime aware HolidayService + CourtService

Holiday struct gains Country (ISO-3166) + Regime ('UPC' | 'EPO' | "")
fields. AppliesTo(country, regime) is the matching rule the new lookup
methods filter through: a row matches when its Country equals the
court's country OR its Regime equals the court's regime. UPC LD München
(DE+UPC) sees DE federal + UPC vacations; LG München (DE+"") sees only
DE federal; UPC LD Paris (FR+UPC) sees FR + UPC. germanFederalHolidays
fallback now country-tagged 'DE' so the per-country filter applies it
only to DE-jurisdictional callers.

Public service methods (IsHoliday, IsNonWorkingDay, AdjustForNonWorking
Days, AdjustForNonWorkingDaysWithReason, findVacationBlock) all take
(country, regime). Cache stays year-keyed — single DB hit per year, all
courts touching that year share it.

New CourtService loads paliad.courts once + answers Lookup(id),
CountryRegime(id, defaultCountry, defaultRegime), All(), ByCourtType(t).
FristenrechnerService.CalcOptions / CalcRuleParams gain CourtID;
EventDeadlineService.Calculate gains courtID. When courtID is empty,
DefaultsForJurisdiction maps the proceeding's existing jurisdiction
column to a sensible (country, regime) default — UPC proceedings get
(DE, UPC), everything else gets DE-only — preserving today's behaviour
for callers that don't yet send a court.

Tests: new TestAppliesTo_CountryRegimeFilter + TestAppliesTo_Rules
cover the cross-product of (DE court / UPC LD München / UPC LD Paris /
LG München) × (DE federal / UPC vacation / FR holiday). Existing tests
threaded through with ('DE', 'UPC') to preserve behaviour they were
written to lock.

cmd/server/main.go

@@ -90,6 +90,7 @@ func main() {
 			log.Printf("refresh deadline_search: %v", err)
 		}
 		holidays := services.NewHolidayService(pool)
+		courts := services.NewCourtService(pool)
 		users := services.NewUserService(pool)
 		projectSvc := services.NewProjectService(pool, users)
 		teamSvc := services.NewTeamService(pool, projectSvc)
@@ -140,8 +141,9 @@ func main() {
 			Rules:          rules,
 			Calculator:     services.NewDeadlineCalculator(holidays),
 			Users:          users,
-			Fristenrechner: services.NewFristenrechnerService(rules, holidays),
-			EventDeadline:  services.NewEventDeadlineService(pool, services.NewDeadlineCalculator(holidays), holidays),
+			Fristenrechner: services.NewFristenrechnerService(rules, holidays, courts),
+			EventDeadline:  services.NewEventDeadlineService(pool, services.NewDeadlineCalculator(holidays), holidays, courts),
+			Courts:         courts,
 			DeadlineSearch: services.NewDeadlineSearchService(pool),
 			EventCategory:  nil, // wired below; cross-link order matters
 			EventType:      eventTypeSvc,