I spent a few minutes checking and can give some quick pointers.
1- You have a large amount of weapon assigned to be melt. Those don't count as available weapon. The melting is also bugged right now, so this probably explain the crashes you've had. I stopped all melting jobs and the fortress is still currently running without issues.
2- The arsenal dwarf was attending a party. That's not acceptable. Never. Especially not with under equiped militia during a siege. After freeing the meeting hall, he proceded to update stockpile records. That's not acceptable either. Changing the bookkeeping setting to lowest made go eat... damn dwarves. So basically, you either need to prepare troops ahead of time (i.e. not when goblins are at your gate) or babysit the arsenal dwarf so actually do his damn job.
3- Stockpiling isn't an issue, just an annoyance. Forbidding everything outside and changing the forbid order (
o,
F) should minimize cancelation spam.
4- The reasons goblins aren't moving in is that they follow their leader. A caged leader means the squad will stick around the trap unless there's an enemy close (also true, somewhat, with wildlife). It isn't because they can't see your dwarves or whatever. Units are omniscient (yet stupid) in DF; if there's a path they KNOW it.
Not much to say about the fortress. You make good use of z levels, which is seldomly the case with new players. Efficiency is greatly improved by proper use of the z axis. There's a few things I could add, but that are mostly a question of play style/preference. Like the fact you have few bedroom created, which is usually something high in my priority list. Nothing strikes me as bad design or planning... that's more than I can say about my own fortresses
edit: BTW, I let the game run while I was typing and it didn't crash after over 2 seasons (and no, my computer isn't running fast, I type slowly). Melting was most likely the problem.