At its core, this game is p good. reminds me a lot of catastrophe x before that game died.
Anyway, as for input/suggestions:
-Currently the only real strategy is ship spam. Winning this way is just. so, so slow as spawn rate/damage/health is always the same for every ship, every engagement early usually ends in like a 1-2 HP advantage overall.
-More ship diversity or things to do with planets other than building ships would make the game more than just a spamfest, as currently if you have 3 planets, just make all 3 ships and you're winning pretty much guaranteed
-The turn timer should scale up slightly for each unit you control (like. two seconds per unit+planet) for when you get a ton of crap on the field
-make clicking on the cell a ship is on select it instead of having to click the ship itself. I found it mildly annoying to slightly miss the ship when I still clicked the correct cell
-highly recommend numbering units whose orders have been given so you can assess which one goes first. mostly applies if you have a lot of them
-Possibly highlight movement conflicts if your ships are going to path through an obstructed square. Its an interesting game mechanic but some notifications about when it is happening would help a lot
But hey, what you've got so far is definitely solid. Its hard to judge what the game will be once some actual content is added, but I'm sure if you keep at it you'll end up with something good in the end!