However, at that time, it was not existing and, if it existed, it would be probably quite hard to put it into the legal system because of the fresh edicts against Germans. In the end, the third Czechoslovak Republic failed because of its rooted nature and kind of deserved its fate. You cannot displace 1.2M of people and try to look as a democratic state (no matter how necessary it was).
There are a number of democratic states that have happily uprooted a lot more people than that, both before, and after WW2. Most of them haven't failed.
Which wouldn't stop anything in and of itself. The current Chinese constitution allows freedom of speech, for example.
1.2M.. I think the current estimates are 2.4M expelled Germans, not counting the expelled Hungarians from Slovakia (many of which later returned and were granted citizenship).
Had it done so, it's very likely that the USSR would have intervened.
The width of the possible scenarios is unsettling, one of them may be Prague turning into European Hiroshima.
That would be unlikely - Czechoslovakia was in Soviet sphere of influence as decided in Yalta and the West was severely outgunned (at least in conventional weapons) by Soviets in Europe.
"The west" was severely outgunned by the west - the largest political party in France in 1948 was PCF, the communist/socialist alliance in Italy almost won that year. Finland remained outside the eastern bloc simply because it was no longer seen as being part of a threat. In the UK the Labour party which tossed out Churchill while he was in Potsdam was busy nationalizing the commanding heights of England's means of production (although they were not as militant as their comrades on the continent of course).
The west was busy trying to hold onto the West, never mind intervening in Prague.
On February 21st, 1948, the non-communist ministers handed in resignations, without any pressure from the communist party. You left that part out. On February 25th the resignations were accepted. This was not a "coup" - they lost the elections in 1946 and decided to abandon the government in a failed power play. Also, as you note, the president of Czechoslovakia in the 1930s, Benes, a non-communist, presided over this.
The militias committed no violence, took over no buildings or the like and were not involved in the cabinet. The majority of Czechs did not find factory workers being armed to defend themselves to be as threatening as you apparently do.
If you really want to see elections being fixed, look at the fixing of the elections in Italy in the same year against the communist/socialist coalition.
Czechoslovak Communist Party was since 1929 an obedient servant of Stalin with zero own will. The chairman Gottwald was a sycophant who later hanged his own friends (Slansky, Reicin) on request from Moscow.
Yes, the coup was nonviolent, much like occupation of Sudetenland 10 years prior, because our elite decided to throw in the towel. There was no one left to defend our democracy against a powerful foe.
"factory workers being armed to defend themselves"
What an incredible load of B.S. People's Militias were Communist equivalent of Iraqi sectarian militias after the ouster of Saddam. They acted as an armed fist of the party for the possible case that democratic politicians decide not to go quietly.
May 1948 elections were a travesty, as were all other elections until 1985 (the last ones under Communist power).
Communists won the election in 1946 and formed a coalition government in which they were the strongest force, but not completely dominant. There were other "bourgeoise" ministers. Unfortunately, Communists controlled the ministry of the interior and cleansed the police of "reactionary elements", thus cementing their control over the civilian law enforcement. Not over the army yet, though.
There were regular elections scheduled for May 1948 and opinion polls were indicating that Communist share of vote is actually going to diminish. So they preempted them by staging a coup supported by People's Militias (a completely illegal armed militia of the party) on February 25, 1948. After that, the democracy was toast and it was full speed towards Stalinism, show trials etc.
Some of the army generals wanted to suppress the coup militarily, but the aging President (Beneš) did not allow that. IDK if it would have been better or worse. Civil wars tend to leave a very toxic legacy.