refactor(channelserver): add numeric column helpers and extract protocol constants

Add readCharacterInt/adjustCharacterInt helpers for single-column
integer operations on the characters table. Eliminates fmt.Sprintf
SQL construction in handlers_misc.go and replaces inline queries
across cafe, kouryou, and mercenary handlers.

Second round of protocol constant extraction: adds constants_time.go
(secsPerDay, secsPerWeek), constants_raviente.go (register IDs,
semaphore constants), and named constants across 14 handler files
replacing raw hex/numeric literals. Updates anti-patterns doc to
mark #4 (magic numbers) as substantially fixed.

server/channelserver/handlers_semaphore.go

@@ -79,9 +79,9 @@ func handleMsgSysCreateAcquireSemaphore(s *Session, p mhfpacket.MHFPacket) {
 			suffix, _ := strconv.Atoi(pkt.SemaphoreID[len(pkt.SemaphoreID)-1:])
 			s.server.semaphore[SemaphoreID] = &Semaphore{
 				name:       pkt.SemaphoreID,
-				id:         uint32((suffix + 1) * 0x10000),
+				id:         uint32((suffix + 1) * raviSemaphoreStride),
 				clients:    make(map[*Session]uint32),
-				maxPlayers: 127,
+				maxPlayers: raviSemaphoreMax,
 			}
 		} else {
 			s.server.semaphore[SemaphoreID] = NewSemaphore(s, SemaphoreID, 1)