fix(litigationplanner): rename upc.apl → upc.apl.unified (HOTFIX, t-paliad-299, m/paliad#130)

mig 134 was inserting code='upc.apl' (2 segments) into paliad.proceeding_types,
which carries paliad_proceeding_code_shape CHECK requiring 3 dot-segments OR
'^_archived_'. Every container restart hit the constraint, rolled the migration
TXN back, and crash-looped paliad.de.

Rename the unified Berufung code to 'upc.apl.unified' (3 segments, satisfies the
constraint, preserves design intent). The pre-existing constraint is a useful
jurisdiction.category.specific invariant — keep it, fix the new row.

Touched only string literals:
- mig 134 up.sql + down.sql (insert, lookups, post-checks)
- frontend/src/verfahrensablauf.tsx (UPC_TYPES code + i18nKey)
- frontend/src/client/verfahrensablauf.ts (APPELLANT_AXIS + APPEAL_TARGET sets)
- frontend/src/client/i18n.ts (DE + EN translation rows)
- frontend/src/i18n-keys.ts (auto-regen via bun build)
- internal/services/lookup_events_test.go (anchor-row assertion)

Verified: `grep -rn "'upc\.apl'\|\"upc\.apl\""` returns zero hits.
go build, bun run build, go test ./... all green.

internal/services/lookup_events_test.go

@@ -137,8 +137,8 @@ func TestLookupEvents(t *testing.T) {
 				t.Errorf("anchor row %s missing endentscheidung target: %v",
 					m.Rule.Name, m.Rule.AppliesToTarget)
 			}
-			if m.ProceedingType.Code != "upc.apl" {
-				t.Errorf("anchor row %s came from %s, want upc.apl",
+			if m.ProceedingType.Code != "upc.apl.unified" {
+				t.Errorf("anchor row %s came from %s, want upc.apl.unified",
 					m.Rule.Name, m.ProceedingType.Code)
 			}
 		}