I work with some ports that have high tidal ranges, it's a big issue, but it's a problem for which many solutions have been developed.
If the vessels are small, they can simply rest on the seabed when the tide goes out. If the vessels are large then you can schedule the ship movements so they won't ground. If the port would completely dry out during low tide you may need to dredge an area in which water will remain when the tide goes out - keep in mind that water won't flow out of a pool when the tide goes out! A tidal barrier can also be built to trap the water in the harbor like a giant lock.
You're right in thinking it's impossible to have docks that work 100% of the time, but I think you are missing that is true for most big ports on Earth too as there can be a 400,000 ton difference in weight between a ship that is ballast, and a ship that is laden. So if a ship is importing to your harbor it could come in on the high tide, offload its cargo, and leave later on a low tide. This is not unusual at all.
One factor that I think you are neglecting is that having such a big tidal range means water is going to be moving fast. That's a significant problem because ship engines can only exert a limited amount of force. It may be extremely difficult or impossible for you to bring a ship into your port during the ebb or have a ship depart during a flood.
You could also build your port on a river or lake connected to the sea, which does not drain when the tide goes out.
So, you have a port with a 25m tidal range that is drying out your port entirely. If you don't have much money, the first step is just to use small boats - they are quick to load/unload so they can arrive and leave quickly, they can sit on the seabed if need be.
If you need to move more tonnage then you might opt to use transshipment - your little boats don't sail all the way to the destination, instead a larger boat waits in deeper water as the boats ferry goods between the port and the boat.
Stronger ships or locks
If that is still unsatisfactory, you are going to have to either develop large vessels which can survive sitting on the seabed during low tide, or create a lock which will hold water in your harbor while the vessel can be loaded/unloaded.
If you absolutely need to be able to move more tonnage, then you have the currently most effective and most expensive option: dredging. Dig a big hole at your harbor so that even at low tide ships can maneuver. Now dig a big trench from your harbor out to the ocean. Both of these need to be deep enough that they always contain enough water. Once you have finished this project ships can sail in and out at any time of day and your import/export ability is maximized. However, that's assuming your ships can actually sail against the tide. In all likelihood the speed of the water is going to be too fast to sail against, so you will still be tidally limited.
Deepwater ports and berths
There's actually some other options that can help your ships deal with tides. The first is building a deep water port. Go out far enough from the high tide line that there is always adequate water, and build your port there. Build a bridge or causeway to connect your deep water port to the city. A cheaper option is to build single berths rather than a whole port. There are a lot of options here; build a jetty with a normal berth at the end, drive some piles and have the ship moore against them, add some heavy anchors with lines connected to buoys on the surface that the ship can connect to. To load the ship either use transshipment as above, or construct conveyer belts or pipelines out to the berths.